JP4185869B2 - Variable valve mechanism - Google Patents

Description

  The present invention relates to a variable valve mechanism that changes a lift amount and a working angle of a valve continuously or stepwise in accordance with an operating state of an internal combustion engine.

  As the variable valve mechanism, as shown in FIG. 8, a seesaw arm 51 is pivotally attached to a rocker arm 50 so as to be swingable at the center thereof, and one end portion and the other end portion of the seesaw arm 51 are different from each other. , 53 is known to change the lift amount of the valve 54 by pressing with different phases (see, for example, Patent Document 1).

Further, as shown in FIG. 9, a support shaft 62 is provided in the vicinity of the two rocker arms 60 including the rollers 61, and a roller 64 that is pressed around the support shaft 62 by a rotating cam 67 is axially attached. An intervening arm 63 and a second intervening arm 66 that is positioned on the left and right of the first interposing arm 63 and respectively presses the rollers 61 are pivotally attached to the first interposing arm 63 and the second interposing arm 66. There is known one provided with a relative angle control mechanism that changes the lift amount and the working angle of the valve 68 by changing the relative angle (see, for example, Patent Document 2).
JP 2002-309918 A JP 2001-263015 A

However, the above variable valve mechanism has the following problems.
(1) Since the rocker arm 50 including the seesaw arm 51 is provided with the rotating cams 52 and 53 on the top of the seesaw arm 51, the internal combustion engine becomes bulky. Furthermore, it is necessary to change the phase of the two rotary cams 52 and 53 to rotate them, and driving is difficult.
(2) Since the rocker arm 60 provided with the roller 61 adds a relative angle control mechanism to the upper part of the roller 61, the internal combustion engine becomes bulky, the number of parts is large, and the assembly is complicated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a variable valve mechanism that solves the above-mentioned problems, is easy to assemble, can be precisely controlled, and has a simple structure and a compact structure.

In order to achieve the above object, the variable valve mechanism according to the present invention includes a pivot support portion and a rotary cam sliding contact portion which are disposed on a rocker arm at substantially the same position or a lower position with respect to the vertical position of the rocker arm. And the sub arm provided with the control cam sliding contact portion is pivotally supported at the pivoted support portion to form a composite rocker arm, and the rotary cam that presses the rotary cam sliding contact portion to swing the sub arm is rotatably provided and controlled. A control cam provided with a cam surface that slides the cam sliding contact portion when the sub arm swings is provided so as to be able to rotate at a small angle, and the cam surface has a non-working surface portion that is equal in distance from the small angle rotation center of the control cam, The working surface portion is continuous with the working surface portion and the distance from the small angle rotation center increases as the distance from the non-working surface portion increases. The small angle rotation center coincides with the pivoted support portion, and the control cam slide is moved when the sub arm swings. While the part slides on the non-working surface part, the pivoted support part remains aligned with the small-angle rotation center and does not lead to rocking of the rocker arm, and if the control cam sliding part slides on the working surface part, The shaft support is configured to shift downward from the small angle rotation center so that the swing of the sub arm is linked to the swing of the rocker arm. When the control cam is controlled to rotate at a small angle in accordance with the operating condition of the internal combustion engine, The sliding start position of the control cam slidable contact portion is changed, and the lift amount and the working angle of the valve are changed by changing the degree and timing of the swing of the sub arm leading to the swing of the rocker arm. To do. In this specification, “upper and lower” means the axial direction of the cylinder of the internal combustion engine (see the direction of the axis A of the cylinder C illustrated in FIG. 4), and “upper” means the direction away from the cylinder and “lower”. Means the direction approaching the cylinder.

  Here, the pivotally supported portion, the rotating cam sliding contact portion, and the control cam sliding contact portion of the sub arm are disposed at “substantially equivalent positions” with respect to the vertical position of the rocker arm, respectively. Not only in the case where they are arranged at the same position (that is, they are arranged side by side so that the entire portion of the sub arm overlaps the side of the rocker arm), but also about 30 mm below the bottom surface of the rocker arm from about 30 mm above the rocker arm upper surface. (I.e., a part of the sub-arm is arranged side by side so as to overlap the side of the rocker arm, but the respective parts are arranged so as to be slightly shifted up and down). Further, the “lower position” is not particularly limited numerically, but is practically up to 50 mm below the bottom surface of the rocker arm due to the size or arrangement of each component. However, when each part is viewed individually, the pivoted support part is pivotally supported by the rocker arm, so that the whole or a part of the pivoted support part (see the embodiment) is arranged at the “substantially equivalent position”. It will be. The rotating cam sliding contact portion is preferably arranged at the “substantially equivalent position” because it is difficult to arrange the rotating cam downward. On the other hand, the control cam sliding contact portion can be changed according to the position where the control cam is disposed, and is not particularly limited downward, so it may be the “substantially equivalent position” or the “lower position”.

The cams surfaces, non-working face is equal distance from the small angular rotation center of the control cam (the base circle), the action surface portion with distance from the small angle rotation center moves away from a continuous non-working face from the non-working face And where the control cam sliding contact part is located on the non-working surface part by aligning the small angle rotation center (fixed point) of the control cam with the pivoted part (swing center) of the sub arm. that controls (either far or near country working surface).

  The shape of the sub arm excluding the pivoted support portion is formed to be narrower than the distance between adjacent rocker arms, and a portion of the sub arm that is pivotally supported directly above the rocker arm is formed. It is preferable that the control cam sliding contact portion and the rotating cam sliding contact portion are formed in the detached portion. This is because no matter how the positions of the control cam sliding contact portion and the rotating cam sliding contact portion are determined, they do not interfere with the rocker arm. Thereby, for example, the positions of the control cam sliding contact portion and the rotating cam sliding contact portion can be made lower than the shaft support portion.

  The rocking of the compound rocker arm and the rocking and tilting of the sub arm may be in different planes. However, for the sake of space efficiency, the rocking of the compound rocker arm and the rocking and tilting of the sub arm should be performed in the same plane. Is preferred.

  The rotating cam sliding contact portion of the sub arm may be a roller that can rotate on a fixed surface. The control cam sliding contact portion of the sub arm may also be a roller that can rotate on a fixed surface. In any case, a fixed surface is preferable from the viewpoint of cost, and a roller rotatably attached to the shaft is preferable from the viewpoint of sliding resistance and wear. In view of the above, it is preferable that at least one of the rotating cam sliding contact portion or the control cam sliding contact portion is a roller that is rotatably attached to the shaft. When both the rotating cam sliding contact portion and the control cam sliding contact portion are rotatable rollers, both rollers may be provided on the same axis or on separate parallel axes. Alternatively, one of the rollers may be a symmetrical plane and the other two rollers may be arranged so that the force received from the rotating cam and the control cam does not cause torsional stress on the sub arm.

  An apparatus for controlling the rotation of the control cam at a small angle is not particularly limited, but an apparatus including a helical spline mechanism, a drive unit using hydraulic pressure, and a control device such as a microcomputer can be exemplified.

  The rocker arm may have a rocking center at the center in the arm length direction or at one end (so-called swing arm). The rocking center may be pivotally supported or pivotally supported. Further, it is preferable that a tappet clearance adjusting mechanism is provided at the center of swinging. When the rocker arm and sub arm swing in the same plane, the present invention is embodied in a type in which the rocker arm swing center is at one end in the arm length direction because the sub arm does not protrude from the rocker arm and space efficiency is good. It is preferable to do. That is, it is preferable that the rocker arm is of a type having a swinging central portion at one end, a shaft support at the center, and a valve pressing portion at the other end.

  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.

  According to the variable valve mechanism of the present invention, there are excellent effects that assembly is simple and precise control is possible, and that the structure is simple and compact.

  The variable valve mechanism is capable of swinging a sub arm provided with a pivot support portion, a rotating cam sliding contact portion, and a control cam sliding contact portion that are substantially equal to or below the rocker arm's vertical position. The shaft is pivotally supported at the shaft support portion to form a composite rocker arm, and a rotary cam that presses the rotary cam sliding contact portion to swing the composite rocker arm is rotatably provided. When the rotary cam sliding contact portion is pressed, the control cam sliding contact portion is provided. A control cam having a cam surface that slides and tilts the sub-arm is provided so as to be rotatable by a small angle. When the control cam is controlled to rotate at a small angle in accordance with the operating condition of the internal combustion engine, the sliding start position of the control cam sliding contact portion on the cam surface changes, and the relative angle of the sub arm with respect to the rocker arm when the composite rocker arm swings is changed. By changing, the lift amount and the working angle of the valve are changed.

  As a concrete mode for changing the sliding start position of the control cam sliding contact portion on the cam surface and changing the degree and timing of the swing of the sub arm to the rocker arm, the cam surface is rotated by a small angle of the control cam. A non-working surface portion having the same distance from the center and a working surface portion that is continuous from the non-working surface portion and that is separated from the small-angle rotation center as it is away from the non-working surface portion. This small angle rotation center is made to coincide with the pivoted support part, and when the sub arm swings, while the control cam sliding part slides on the non-working surface part, the pivoted support part remains matched with the small angle rotation center. The rocker arm will not swing. Further, when the control cam sliding contact portion slides on the action surface portion, the pivoted support portion shifts downward from the small angle rotation center, and the swing of the sub arm leads to the swing of the rocker arm. The rocking of the rocker arm and the rocking and tilting of the sub arm are performed in the same plane, and the rotating cam sliding contact portion and the control cam sliding contacting portion are rollers rotatably mounted on the sub arm.

  1 to 6 show the variable valve mechanism of the first embodiment. In this mechanism, two rocker arms 1 of a swing arm type are arranged so as to be arranged at intervals, and a base end portion 1a of the two rocker arms 1 is pivotally supported by a rocker shaft 2 and becomes a rocking center portion of the rocker arm 1. (The base end portion 1a of each rocker arm 1 may have a concave spherical surface formed on the same portion supported by a pivot.) The base end portions 1 a of the two rocker arms 1 are connected by a connecting portion 1 b so as to wrap the rocker shaft 2, and are parts having the two rocker arms 1. A valve pressing portion 3 that presses the proximal end portion of the valve 5 is provided at the distal end portion 1 c of the rocker arm 1. A shaft support portion 4 that is recessed in a substantially semi-cylindrical shape extending in parallel with the rocker shaft 2 is provided at a substantially central portion in the length direction of the two rocker arms 1. In the following description, for the sake of convenience, the distal end direction (right direction in FIGS. 1 to 5) of the rocker arm 1 is referred to as “front” or front or front side as required, and the proximal direction (also left direction) is referred to as “rear” or It will be referred to as rear or rear as required.

  The variable valve mechanism is characterized in that a pivotal support 11 at the upper end of the subarm 10 is pivotally supported on the pivotal support 4 of the rocker arm 1 to form a composite rocker arm 9, and substantially the entire subarm 10 is substantially the same as the rocker arm 1. In other words, they are located at the same or lower positions. Further, the sub arm 10 includes a rotating cam sliding contact portion 12 and a control cam sliding contact portion 13, and a rotating cam 7 that presses the rotating cam sliding contact portion 12 and swings the composite rocker arm 9 is rotatably provided. The control cam 15 provided with the cam surface 18 that slides the control cam sliding contact portion 13 and tilts the sub arm 10 when the rotating cam sliding contact portion 12 is pressed is provided so as to be rotatable by a small angle. These are described in detail below.

The sub-arm 10 has a pair of opposed plate-shaped side surfaces 14 opposed to each other, a supported shaft portion 11 projecting vertically from the upper end of each of the side surface portions 14 coaxially outward, and opposed side surfaces. A rotating cam sliding contact portion 12 composed of a roller rotatably mounted so as to be sandwiched between the middle portions of the portion 14 and a roller rotatably mounted so as to be sandwiched between the lower ends of the opposing side surface portions 14 And a control cam sliding contact portion 13. The sub-arm 10 is pivotally supported by the pivotal support 4 so that the pivoted support 11 can swing. The pivoted support 11 overlaps the vertical position of the rocker arm, and the rotary cam sliding contact 12 and the control cam at the uppermost position. The sliding contact portion 13 is disposed in a range from the upper end of the rocker arm to about 20 mm above. Further, the sub arm enters the space between the two rocker arms 1 in a non-contact manner and extends downward, and makes the control cam sliding contact portion 13 contact the cam surface 18 of the cam portion 17 of the control cam 15 described below. In other words, the sub arm 10 excluding the pivot support 11 is formed to be narrower than between the rocker arms 1, and the sub arm 10 does not interfere with the rocker arm 1, so that the control cam sliding contact portion 13 is positioned below the pivot support 4. ing. The center axis of the pivoted support portion 11 that is pivotally supported by the pivot support portion 4 is the swing center Q of the sub arm 10.
In this example, the pivoted support portion 11, the rotating cam sliding contact portion 12, and the control cam sliding contact portion 13 of the sub arm 10 have a “<” shape arrangement (side view) in which the rotating cam sliding contact portion 12 projects forward. ing. The sub arm 10 interposed between the rotary cam 7 and the shaft support 4 is designed so that the distance between the rotation cam 7 and the shaft support can be changed when tilted.

  A single camshaft 6 is rotatably supported on the side of the sub arm 10. The camshaft 6 is formed with a rotating cam 7 that lifts the valve 5 by pressing the rocker arm 1 through the sub arm 10 by pressing the rotating cam sliding contact portion 12 to the side. The rotating cam 7 includes a base circle 7a, a nose gradually increasing portion 7b in which the protruding amount gradually increases, a nose 7c having the maximum protruding amount, and a nose gradually decreasing portion 7d in which the protruding amount gradually decreases. The rotation direction of the rotary cam 7 is a direction in which the nose 7c approaches the rotary cam sliding contact portion 12 from above (counterclockwise in the illustrated example). The rotation cam 7 is arranged such that the rotation center of the rotation cam 7 (the axis of the camshaft 6) does not rise above the upper end of the sub arm 10 at the uppermost position (FIGS. 4A and 5A). Is arranged. In this embodiment, the rotating cam sliding contact portion 12 provided in the sub arm 10 is located substantially equal to the vertical position of the rocker arm 1, so that the rotating cam 7 is positioned substantially on the side of the rocker arm 1. It will also be that.

  The control cam 15 includes a base circular cam portion 17 having a protrusion, and a connecting portion 16 that connects the adjacent cam portions 17 and extends in parallel with the supported shaft portion 11 above the supported shaft portion 11 of the sub arm 10. A small angle rotation device (not shown) is provided so as to be able to rotate at a small angle in accordance with the operating state of the internal combustion engine. The cam portion 17 is located above the interval between the two rocker arms 1, and is arranged so that the protruding portion of the cam portion 17 enters the interval between the opposing side portions 14 of the sub arm 10. And rotate at a small angle. The small-angle rotation center R of the control cam 15 is the central axis of the base circle portion. The cam portion 17 includes a cam surface 18 on which the control cam sliding contact portion 13 from the front surface of the protruding portion on the peripheral surface to the front base circle abuts. The cam surface 18 is a non-operating surface portion 18a having a convex arc surface shape in which the circumferential surface of the base circle in the front half is substantially equal in distance to the small angle rotation center R of the control cam 15, and the front surface of the projection portion in the rear half is The acting surface portion 18b is separated from the small angle rotation center R of the sub arm 10 toward the rear side. The sub arm 10 can swing independently of the small angle rotation. The connecting portion 16 has an upwardly convex bow shape so as not to come into contact with the rocker arm 1 and the sub arm 10 when the control cam 15 rotates at a small angle. The connecting part 16 and the cam part 17 may be integrally formed.

  Further, the control cam 15 is controlled to rotate at a small angle by a small angle rotating device, and the orientation angle of the cam portion 17 is continuously or stepwise within a range within one rotation (at least two steps, preferably three steps, more preferably Can be changed to four or more stages). When the orientation angle of the cam portion 17 changes, the contact position P between the control cam sliding contact portion 13 and the cam surface 18 changes, and the contact point between the rotating cam sliding contact portion 12 and the rotating cam 7 changes vertically. As a result, the sliding start position that is the contact position P of the control cam sliding contact portion 13 on the cam surface 18 changes, and the degree and timing at which the swing of the sub arm 10 is linked to the swing of the rocker arm 1 changes. The small angle rotation center R (fixed point) of the cam 15 is made to coincide with the pivoted support portion 11 (swing center) of the sub arm 10, and where the sliding start position of the control cam sliding contact portion 13 is set on the non-working surface portion 18a ( It is possible to control whether the working surface portion is close or far. Thereby, the lift amount, the working angle, and the timing of the valve 5 are changed by changing the relative angle of the sub arm 10 with respect to the rocker arm 1 when the composite rocker arm 9 is swung.

  Further, in the composite rocker arm 9 of this embodiment, even when the sub arm 10 is swung, while the control cam sliding contact portion 13 is sliding on the non-working surface portion 18a, the combined rocker arm 9 is the swivel center Q of the sub arm 10. Since the shaft support portion 11 does not move while being aligned with the small angle rotation center R of the control cam 15, the swing of the sub arm 10 does not lead to the swing of the rocker arm 1. When the control cam sliding contact portion 13 slides on the action surface portion 18 b, the pivoted support portion 11 that is the swing center Q of the sub arm 10 moves along the small angle rotation center of the control cam 15 with the swing of the sub arm 10. Since it shifts downward from R, the swing of the sub arm 10 is linked to the swing of the rocker arm 1.

  In the small angle rotating device, for example, a piston provided with a helical spline moves in the axial direction while rotating at a predetermined angle by hydraulic pressure, and the rotation rotates the control cam 15, thereby rotating the orientation angle of the cam portion 17 once. It is structured to change within the range, and is controlled by a control device such as a microcomputer based on a detection value from a rotation sensor of an internal combustion engine, an accelerator opening sensor or the like. The small angle rotating device may be one using an electric motor such as a step motor.

The variable valve mechanism configured as described above operates as follows.
4 (a) and 4 (b) show an operating condition where the maximum lift amount and the maximum operating angle are required. FIG. 4 (a) shows the base circle 7a of the rotating cam 7 where the rotating cam sliding contact portion 12 is provided. 4B shows the time when the nose 7c comes into contact with the rotating cam sliding contact portion 12 (so-called nose time). Under this operating condition, the projecting portion of the cam portion 17 is controlled to rotate at a lower angle by the small angle rotation control of the control cam 15, and the sub arm 10 is displaced to the lowest position.

At the base of FIG. 4A, the projection portion of the cam portion 17 is inclined downward by the small-angle rotation control, and the contact point between the rotary cam sliding contact portion 12 and the rotary cam 7 is (a minute lift described later). At the same time (in comparison with FIG. 5), the control cam sliding contact portion 13 enters between the two rocker arms 1 (the control cam sliding contact portion 13 is in contact with the control cam 15). . This is the swing start position of the sub arm 10 under the same operating condition. At this time, the contact position P of the control cam sliding contact portion 13 on the cam surface 18 is at the rear end portion of the non-operation surface portion 18a, and the swing center Q of the sub arm 10 and the rotation center R of the control cam 15 coincide. Since the rocker arm 1 is not yet pushed down, the lift of the valve 5 does not occur. When the nose gradually increasing portion 7b comes into contact with the rotating cam sliding contact portion 12 between FIG. 4A and FIG. 4B, the rotating cam 7 starts to press the rotating cam sliding contact portion 12, The sub arm 10 swings rearward about the swing center Q at the upper end, and the control cam sliding contact portion 13 starts to slide downward along the cam surface 18 (the control cam sliding contact portion 13 on the cam surface 18). The contact position P starts to move downward.) Therefore, the sub arm 10 starts to swing around the swing center Q, and the contact position P of the control cam sliding contact portion 13 on the cam surface 18 moves backward while the shaft support portion 11 presses the shaft support portion 4. The position of the swing center Q starts to be displaced rearward and downward from the rotation center R by being applied to the surface portion 18b, the rocker arm 1 begins to swing forward and downward about the rocker shaft 2, and the lift of the valve 5 starts.
4B, the rotating cam 7 presses the rotating cam sliding contact portion 12, and the sub arm 10 swings backward (as described above, the control cam sliding contact portion 13 and the rocker arm 1 are separated from each other). Do not interfere). For this reason, the contact position P of the control cam sliding contact portion 13 on the cam surface 18 retreats the action surface portion 18b in the distal direction, so that the sub-arm 10 tilts while the shaft support portion 11 presses the shaft support portion 4 and swings. The position of the moving center Q is displaced downward maximally around the rocker shaft 2 and the composite rocker arm 9 swings maximally downward, so that the lift amount L of the valve 5 reaches the maximum value Lmax. Further, the contact position P at the base is at the rear end portion of the non-working surface portion 18a, and the valve 5 is lifted in a wide range from when the sub arm 10 starts to be displaced to the maximum, so that the working angle is maximum. Become. (See FIG. 6).

  5 (a) and 5 (b) show operating conditions that require a minute lift amount and a minute working angle, FIG. 5 (a) shows the base time, and FIG. 5 (b) shows the nose time. Each is shown. Under this operating condition, the protruding portion of the cam portion 17 is controlled above the time of FIG. 4 by the small angle rotation control of the control cam 15, so that the sub arm 10 is at the base time as shown in FIG. At substantially the same position, it is displaced only up to the position above the time of FIG.

At the base of FIG. 5 (a), the protruding portion of the cam portion 17 is positioned on the upper rear side with respect to the time of FIG. 4 by the small angle rotation control, and the contact point between the rotating cam sliding contact portion 12 and the rotating cam 7 is The control cam sliding contact portion 13 enters between the two rocker arms 1 (compared with the aforementioned maximum lift (as compared with FIG. 4)) (the control cam sliding contact portion 13 is connected to the control cam 15). Abut). This is the swing start position of the sub arm 10 under the same operating condition. At this time, the contact position P of the control cam sliding contact portion 13 on the cam surface 18 is in the middle of the non-operation surface portion 18a (away from the operation surface portion 18b than in the case of FIG. 3). Since Q and the rotation center R of the control cam 15 coincide with each other and the rocker arm 1 is not yet pushed down, the lift of the valve 5 does not occur. 5A to 5B, the nose gradually increasing portion 7b comes into contact with the rotary cam sliding contact portion 12. When the nose in FIG. 5B is reached, the rotary cam 7 is The rotary cam sliding contact portion 12 starts to be pressed, the sub arm 10 swings backward about the swing center Q at the upper end, and the control cam sliding contact portion 13 begins to slide downward along the cam surface 18 ( The contact position P of the control cam sliding contact portion 13 on the cam surface 18 starts to retreat). Therefore, the sub arm 10 starts to swing around the swing center Q, and the contact position P of the control cam sliding contact portion 13 on the cam surface 18 moves backward and is applied to the action surface portion 18b, and the position of the swing center Q is The rocker arm 1 starts to be slightly displaced rearward and downward, the rocker arm 1 starts to slightly swing downward about the rocker shaft 2, and the valve 5 starts to lift.
Therefore, the sub arm 10 swings and displaces downward, but swings from the swing start position, which is the middle portion of the non-working surface portion 18a, so that the contact position P of the control cam sliding contact portion 13 on the cam surface 18 acts. It advances only to the point where it starts to face the surface portion 18b. For this reason, the position of the swing center Q of the sub arm 10 is displaced only up to the upper side of FIG. Therefore, the composite rocker arm 9 only swings slightly forward and downward, and the lift amount of the valve 5 becomes very small. Further, since the positional relationship between the rotary cam 7 and the sub arm 10 does not change due to the small angle rotation of the control cam 15, even when the lift amount of the valve 5 is the maximum as shown in FIG. Even so, the timing of the peak lift is the same. (See FIG. 6).

  Note that, under an operating situation where an intermediate lift amount / working angle between FIG. 4 and FIG. 5 is required, the cam portion 17 is moved to an intermediate position between FIG. 4 and FIG. By performing small-angle rotation control continuously or stepwise, an intermediate lift amount / working angle / timing can be obtained continuously or stepwise as shown in FIG.

  Subsequently, under an operating condition that requires lift suspension, the protruding portion of the cam portion 17 is controlled further upward than in FIG. 5 by the small-angle rotation control of the control cam 15. When the rotary cam 7 is a base, the sub arm 10 is substantially at the same position as that of each base shown in FIGS. 4A and 5A, and the control cam sliding contact portion 13 contact position P on the cam surface 18 is as shown in FIG. The non-operating surface portion 18a is further away from the operating surface portion 18b of the cam surface 18 than at the time of the above. When the rotary cam 7 is in the nose state, the sub arm 10 swings from the swing start position, which is the non-working surface portion 18a at a position far away from the working surface portion 18b. Since it only slides on the action surface portion 18a, it does not swing around the swing center Q, and the swing center Q is not displaced. Therefore, the rocker arm 1 does not swing and is in a lift rest state.

  According to the variable valve mechanism of the present embodiment configured as described above, the lift amount, the working angle, and the operating angle of the valve 5 can be obtained by rotating only one camshaft 6 without greatly changing the conventional drive system. The timing can be changed continuously or stepwise. Further, a variable valve mechanism shown in FIG. 7A in which the rotary cam 67 directly presses the roller 61 as the cam corresponding portion of the rocker arm 60 to lift the valve 68, or an improved roller 61 and the rotary cam. Compared with the variable valve mechanism shown in FIGS. 7B, 8 and 9 in which a member for precisely controlling the lift amount of the valve 68 is sandwiched between the variable valve mechanism of FIG. Since the mechanism can sandwich the sub arm 10 and the control cam 15 as a member for precisely controlling the lift amount of the valve 5 and can lower the position of the rotary cam 7, a compact variable valve with a reduced height. A mechanism can be formed. For this reason, the vehicle mounting property of the variable valve mechanism can be improved. In particular, in this embodiment, the position of the cam portion 17 is made lower than the shaft support portion 4 so that the control cam sliding contact portion 13 can enter between the two rocker arms 1, so that the sub arm 10 extending vertically is arranged lower. Therefore, it is easy to arrange the rotary cam 7 lower. In addition, the number of parts is small and assembly is easy.

In addition, this invention is not limited to the structure of the said Example, For example, as follows, it can also change and actualize in the range which does not deviate from the meaning of invention.
(1) Change the configuration and control method of the small-angle rotating device as appropriate.
(2) Use a rocker arm with a rocking center at the center.
(3) Change the shape of the sub-arm 10 as appropriate.
(4) Change the shape of the control cam 15 as appropriate.

It is a perspective view which shows the variable valve mechanism based on the Example of this invention. It is a perspective view which shows the state which decomposed | disassembled the principal part of the mechanism. (A) is a side view and (b) is a bb cross-sectional view of (a) showing the same mechanism. FIG. 4A is a cross-sectional view at the time of base, and FIG. 4B is a cross-sectional view at the time of nose showing the operation when the maximum lift amount and the maximum operating angle of the mechanism are required. FIG. 5A is a cross-sectional view at the time of base, and FIG. 5B is a cross-sectional view at the time of nose, showing the operation of the mechanism when a minute lift amount and a maximum operating angle are required. It is a graph which shows the lift amount of a valve | bulb obtained by the variable valve mechanism based on a present Example, a working angle, and timing. The bulkiness of a variable valve mechanism is shown, (a) is a side view of a conventional variable valve mechanism, (b) is a side view of a conventional variable valve mechanism, and (c) is a variable valve according to this embodiment. It is a side view of a mechanism. It is a perspective view which shows the conventional variable valve mechanism. It is a perspective view which shows the conventional variable valve mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rocker arm 2 Rocker shaft 4 Shaft support part 5 Valve 6 Cam shaft 7 Rotating cam 9 Composite rocker arm 10 Sub arm 11 Shaft support part 12 Rotating cam sliding contact part 13 Control cam sliding contact part 15 Control cam 17 Cam part 18 Cam surface

Claims (3)

A rocker arm swings a sub arm provided with a pivoted support portion, a rotating cam sliding contact portion, and a control cam sliding contact portion, which are disposed at substantially the same position or a lower position with respect to the vertical position of the rocker arm. A compound rocker arm can be pivotally supported.
A rotary cam that presses the rotary cam sliding contact portion and swings the sub arm is provided rotatably.
A control cam provided with a cam surface that slides the control cam sliding contact portion when the sub arm swings is provided so as to be rotatable at a small angle.
The cam surface includes a non-working surface portion having the same distance from the small-angle rotation center of the control cam, and a working surface portion that is continuous from the non-working surface portion and is separated from the non-working surface portion by a distance from the small-angle rotation center. Consisting of
The small angle rotation center is made to coincide with the pivoted support part,
When the sub arm swings, while the control cam sliding contact portion slides on the non-working surface portion, the pivot support portion remains aligned with the small angle rotation center, and does not lead to rocker arm swinging. When the control cam sliding contact portion slides on the action surface portion, the pivot support portion is shifted downward from the small angle rotation center, and the swing of the sub arm is connected to the swing of the rocker arm,
When the control cam is controlled to rotate at a small angle according to the operating condition of the internal combustion engine, the sliding start position of the control cam sliding contact portion on the cam surface changes, and the swing of the sub arm leads to the swing of the rocker arm And a variable valve mechanism configured to change the lift amount and operating angle of the valve by changing the timing. Claim 1 Symbol placement of the variable valve mechanism is performed in the same plane as the swinging and tilting of the rocking of the rocker arm sub-arm. 3. The variable valve mechanism according to claim 1, wherein at least one of the rotating cam sliding contact portion or the control cam sliding contact portion is a roller rotatably attached to the sub arm.

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