JP2008215163A - Variable valve mechanism for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve mechanism for an internal combustion engine, which changes the opening/closing characteristics of a suction valve within such a wide range as to be required, and eliminates variation of the opening/closing characteristics of the suction valve among cylinders. <P>SOLUTION: The variable valve mechanism 6 includes: an intermediate member 12 that swings about a shaft 11 by being pushed by a rotating inlet cam 4a so as to press the suction valve 2 in a valve opening direction; and a drive mechanism 13 for moving the shaft 11 in parallel with the intermediate member 12 in a diameter direction. The intermediate member 12 comprises a first link 12a swingably connected to the shaft 11 and a second link 12b rotatably connected to the first link 12a via a pin 14. The second link 12b has a cam-side contact portion 15, a profile surface 16, and a valve-side contact portion 21. The variable valve mechanism 6 includes an adjusting mechanism which adjusts the position of the shaft 11 in the diameter direction for each cylinder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism for an internal combustion engine.

  Some internal combustion engines, such as automobile engines, are provided with a variable valve mechanism that can change open / close characteristics such as the maximum lift amount, operating angle, and valve timing (timing at which the maximum lift amount is obtained) of the intake valve. It has been.

  Here, when the maximum lift amount and the operating angle are made variable as the opening / closing characteristics of the intake valve, the maximum lift amount and the operating angle of the intake valve, for example, as indicated by Y1 in FIG. Are changed to the increase side or the decrease side in a synchronized state. Specifically, when the required value of the intake air amount of the internal combustion engine is large, such as during high load operation, the maximum lift amount and operating angle of the intake valve are maximized to satisfy the request. On the other hand, when the required value of the intake air amount of the internal combustion engine is small, such as during idling, the maximum lift amount and operating angle of the intake valve are minimized according to the request. Therefore, the maximum lift amount and operating angle of the intake valve are controlled to be maximized during high-load operation, and are controlled to gradually decrease as the engine load decreases toward idle operation.

  By the way, if the maximum lift amount and operating angle of the intake valve are maximized, the opening timing of the intake valve is advanced and the valve overlap between the intake valve and the exhaust valve becomes large, which may adversely affect the engine operation. . In addition, when the maximum lift amount and operating angle of the intake valve are minimized during idle operation, the intake valve closing timing is advanced to reduce the pumping loss of the internal combustion engine, but in order to realize further reduction of the pumping loss. It is preferable to further advance the closing timing of the intake valve.

  Note that the pumping loss of the internal combustion engine can be reduced by advancing the closing timing of the intake valve during idle operation for the following reason. That is, when the maximum lift amount and operating angle of the intake valve are minimized during idle operation and the valve closing timing is changed to the advance side, the valve closing timing of the intake valve is reached during the intake stroke. In this state, as the closing timing of the intake valve is advanced, the amount of gas present in the combustion chamber during the compression stroke decreases, and the pressure in the combustion chamber during the compression stroke decreases. The pumping loss is reduced.

  Therefore, an ideal change in the opening / closing characteristics of the intake valve in a situation where the operating state of the internal combustion engine changes from a high load operation to an idle operation is a change as indicated by an arrow Y2 in FIG. That is, when the engine load is reduced from high load operation to idle operation, the valve timing of the intake valve is changed from the most advanced angle state as the maximum lift amount and operating angle of the intake valve gradually decrease from the maximum value. Change toward the most advanced state. As a result, the opening / closing characteristics of the intake valve change as shown by the arrow Y2 in FIG.

In order to realize such variable opening / closing characteristics of the intake valve, it is conceivable to employ a variable valve mechanism as disclosed in Patent Document 1, for example.
The variable valve mechanism is configured by an intermediate member that is pushed by a rotating cam and swings around a shaft and presses the intake valve in the valve opening direction through the swing, and a contact portion between the intermediate member and the cam side. A drive mechanism that translates the shaft together with the intermediate member in the radial direction so that a certain cam side contact portion is displaced forward or backward in the rotation direction of the cam. The mediating member is provided with a profile surface for pressing the intake valve in the valve opening direction.

Regarding this profile surface, the distance in the opening / closing direction of the intake valve between the valve side contact portion, which is a contact portion with the intake valve side, and the cam side contact portion changes as the shaft moves by the drive mechanism. It is estimated that it is formed. More specifically, the intake air between the valve-side contact portion and the cam-side contact portion becomes larger as the shaft and the mediating member are largely translated in the direction in which the cam-side contact portion is displaced rearward (advance angle side) in the cam rotation direction. It is presumed that the profile surface is formed so that the distance in the valve opening / closing direction is shortened.
JP-A-7-293216 (FIGS. 4 to 6, paragraphs [0022], [0023], [0024])

  By adopting the variable valve mechanism, it is possible to realize a variable opening / closing characteristic such that the valve timing is advanced while reducing the maximum lift amount and the operating angle as the variable opening / closing characteristic of the intake valve.

  However, in the variable valve mechanism, the range in which the valve timing can be made variable is limited, and when the valve timing is advanced at the time of transition to idle operation, the advance angle is set to the pumping loss of the internal combustion engine. There is a high possibility that it cannot be carried out to a degree sufficient for the reduction of the above. This is due to the parallel movement of the shaft and the intermediate member for making the valve timing of the intake valve variable, that is, the parallel movement of the shaft and the intermediate member for displacing the cam side contact portion of the intermediate member forward or backward in the rotational direction of the cam. This is related to the limited space on the internal combustion engine for doing so. That is, if the variable range of the valve timing is widened so that the advance timing of the valve timing of the intake valve is implemented to the above-described sufficient level, the space used for the displacement of the mediating member when the shaft and the mediating member are translated. Becomes larger and the mediation member protrudes from the space where the translation can be allowed. Further, when the mediating member swings when opening and closing the intake valve, the mediating member is more likely to protrude from the space. For this reason, the range in which the valve timing can be made variable must be kept small, and it becomes difficult to carry out the advance timing of the valve timing to the above-described sufficient level when shifting to idle operation.

  In addition, when the variable valve mechanism is applied to a multi-cylinder internal combustion engine, in order to change the opening / closing characteristics of the intake valve simultaneously and in the same manner in each cylinder, the intermediation of each cylinder with respect to a single shaft common to each cylinder. It is conceivable to connect the members in a swingable manner. In this case, by moving the one shaft in parallel, all the mediating members of each cylinder can be translated at the same time, and the opening / closing characteristics of the intake valves can be varied simultaneously in the same manner in each cylinder. Become. Although it is possible to change the opening / closing characteristics of the intake valve simultaneously and in the same manner in each cylinder in this way, variations in the opening / closing characteristics of the intake valve occur between cylinders due to the crossing of the dimensions of the intake valve and its peripheral components. In this case, the variable valve mechanism cannot eliminate the variation in the opening / closing characteristics of the intake valve among the cylinders. Therefore, even if the opening / closing characteristics of the intake valve are optimally adjusted in any one of the cylinders, the opening / closing characteristics of the intake valve are not appropriate in other cylinders.

  The present invention has been made in view of such circumstances, and its purpose can be performed over a wide range to the extent that the opening / closing characteristics of the intake valve are required. An object of the present invention is to provide a variable valve mechanism for an internal combustion engine that can eliminate variations among cylinders.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, an intermediate member that is pushed by a rotating cam and swings around the shaft and presses the intake valve in the valve opening direction through the swing, A drive mechanism that translates the shaft in the radial direction together with the mediating member so that a cam side contact portion that is a contact portion with the cam side is displaced forward or backward in the rotation direction of the cam; A profile surface for pressing the intake valve in the valve opening direction is provided, and the intake valve between the valve side contact portion that is a contact portion with the intake valve side and the cam side contact portion is provided with respect to the profile surface. In the variable valve mechanism of the internal combustion engine, the distance in the opening / closing direction of the internal combustion engine is configured to change with the parallel movement of the shaft by the drive mechanism. The mediating member is connected to the first shaft via a first link that can swing around the shaft and a pin that extends in the same direction as the shaft with respect to the first link. And the cam-side contact portion and the second link on which the profile surface is formed, and the drive mechanism moves the shaft between the first displacement end position and the second displacement end position. The first displacement end position is set to a position where the following (a) and (b) can be realized, and the second displacement end position is set to the following (c) and ( d) is set to a feasible position,
(A) When the cam side contact portion is in contact with the base circle portion of the cam, the first link and the second link are extended, and the cam side contact portion of the second link is (B) Based on the fact that the cam side contact portion is pushed by the nose of the cam, the connecting portion between the first link and the second link is the cam. The first and second links bend so as to protrude in a direction opposite to the direction of the intake valve pressing by (c) When the cam side contact portion is in contact with the base circle portion of the cam, The first and second links are bent so that the connecting portion with the second link protrudes in the pressing direction of the intake valve due to the nose of the cam, and the cam side contact portion rotates with respect to the cam. (D) The second link in which the first link and the second link are extended when the cam side contact portion is located at the nose apex portion of the cam. When the shaft is at the second displacement end position, the distance in the opening / closing direction of the intake valve between the cam side contact portion and the valve side contact portion is maximum, and the shaft is in the second position. The gist of the present invention is that the distance becomes shorter as the distance from the first displacement end position approaches the first displacement end position.

  According to the above configuration, the cam side contact portion of the second link is in contact with the base circle portion of the cam, and the shaft is displaced between the first displacement end position and the second displacement end position. Then, the cam side contact portion is displaced between the portion on the front side in the rotation direction and the portion on the rear side in the rotation direction in the base circle portion of the cam. As a result, the valve timing of the intake valve (the timing at which the maximum lift amount occurs) changes. Further, when the shaft is displaced between the first displacement end position and the second displacement end position, the positional relationship between the first link and the second link extends as shown in (a) above. And the bent state as shown in (c) above. As described above, when the positional relationship between the first link and the second link is changed, both of them are bent so that the shaft is displaced between the first displacement end position and the second displacement end position. And the space used for the displacement of the second link is kept small.

  On the other hand, when the positional relationship between the first link and the second link is extended as shown in (a) above, if the cam-side contact portion of the second link is pushed by the nose of the cam, the first link And the second link are bent as shown in (b) above. Further, when the positional relationship between the first link and the second link is bent as shown in (c) above, if the cam side contact portion of the second link is pushed by the nose of the cam, the cam side The first link and the second link remain bent until the contact portion comes into contact with the nose apex portion of the cam. Since the first link and the second link are bent even when the cam side contact portion is pushed by the nose of the cam in this way, the first and the second when the cam side contact portion is pushed by the nose of the cam. The space used for the displacement of the second link is also kept small.

  Thus, even if the variable range of the valve timing is widened so that the advance timing of the valve timing of the intake valve is sufficient to reduce the pumping loss of the internal combustion engine, the shaft is positioned at the first displacement end position. When displacing between the second displacement end positions, whether or not the cam side contact portion is pushed by the nose of the cam, the first and second links have spaces for their displacement. As a result, it is possible to suppress the protrusion from the space secured on the internal combustion engine. Therefore, the range in which the valve timing of the intake valve can be made variable does not need to be kept small, and the advance timing of the valve timing can be implemented to the above-described sufficient degree. In other words, the opening / closing characteristics of the intake valve can be varied over a wide range as required.

  According to a second aspect of the invention, in the first aspect of the invention, the shaft, the first link, the pin, and the second link are provided for each cylinder of an internal combustion engine, and the drive mechanism is provided for each of the above-described driving mechanisms. The shafts of the cylinders are integrally translated, and the shafts of the cylinders can be individually finely adjusted by adjusting mechanisms provided for the cylinders in the radial direction.

  According to the above configuration, through the integral translation of the shaft of each cylinder by the drive mechanism, all the mediating members of each cylinder are translated at the same time, and the opening / closing characteristics of the intake valves can be changed simultaneously and in the same manner in each cylinder. Will come to be. When the intake valve opening / closing characteristics vary among cylinders due to the crossing of the dimensions of the intake valve and its peripheral parts, the radial position of the shaft of each cylinder is adjusted using an adjustment mechanism provided for each cylinder. Fine adjustment is performed individually, so that variations in the opening / closing characteristics of the intake valve among the cylinders can be eliminated.

  According to a third aspect of the present invention, an intermediate member that is pushed by the rotating cam and swings around the shaft and presses the intake valve in the valve opening direction through the swing, and a contact portion between the intermediate member and the cam side A drive mechanism that translates the shaft in the radial direction so that the cam side contact portion is displaced forward or backward in the rotational direction of the cam, and the intermediate member is formed with a profile surface that contacts the intermediate member. With respect to this profile surface, the distance in the opening / closing direction of the intake valve between the valve side contact portion, which is a contact portion with the intake valve side, and the cam side contact portion is determined by the parallel movement of the shaft by the drive mechanism. In the variable valve mechanism of the internal combustion engine formed so as to change with the above, the drive mechanism is the shaft provided for each cylinder of the internal combustion engine The first displacement end position and the second displacement end position are integrally displaced, and the cam side contact portion contacts the base circle portion of the cam with respect to the first displacement end position. The contact is set so that the contact is made with respect to the cam at a portion on the rear side in the rotational direction. With respect to the second displacement end position, the cam side contact portion is the base circle of the cam. When contacting the portion, the contact is set so that the contact is made at the portion on the front side in the rotational direction with respect to the cam, and the shaft position is the second displacement with respect to the profile surface of the mediating member. When in the end position, the distance in the opening and closing direction of the intake valve between the cam side contact portion and the valve side contact portion is maximized, and the shaft position is changed from the second displacement end position to the first displacement end position. The closer the distance is It is formed so that the shorter shaft of each cylinder was summarized in that there is a possible fine adjustment individually by adjusting mechanism provided its radial position in each cylinder.

  According to the above configuration, through the integral translation of the shaft of each cylinder by the drive mechanism, all the mediating members of each cylinder are translated at the same time, and the opening / closing characteristics of the intake valves can be changed simultaneously and in the same manner in each cylinder. Will come to be. When the intake valve opening / closing characteristics vary among cylinders due to the crossing of the dimensions of the intake valve and its peripheral parts, the radial position of the shaft of each cylinder is adjusted using an adjustment mechanism provided for each cylinder. Fine adjustment is performed individually, so that variations in the opening / closing characteristics of the intake valve among the cylinders can be eliminated.

  According to a fourth aspect of the present invention, in the second or third aspect of the invention, the adjusting mechanism rotates the shaft around a center line parallel to the axis of the shaft to thereby adjust the radial position of the shaft. The gist is to adjust.

  According to the above configuration, the function required for the adjustment mechanism to finely adjust the radial position of the shaft of each cylinder is only the function of rotating the shaft around a center line parallel to the axis of the shaft. Therefore, it is not necessary to use complicated parts for the mechanism.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is applied to a multi-cylinder engine for an automobile will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing a structure around an intake valve 2 of a predetermined cylinder in a cylinder head 1 of an engine. The intake valve 2 opens and closes so as to communicate and block the intake passage of the engine and the combustion chamber. The cylinder head 1 is provided with an intake camshaft 4 for driving the intake valve 2, and an intake cam 4 a is fixed to the intake camshaft 4. When the intake camshaft 4 rotates together with the intake cam 4a through rotation transmission from the engine crankshaft, the intake valve 2 opens and closes through the rotation of the intake cam 4a.

  In the cylinder head 1 of the engine, a variable valve mechanism 6 is provided between the intake cam 4a and the intake valve 2 to vary the opening / closing characteristics of the intake valve 2. The variable valve mechanism 6 makes the maximum lift amount, the operating angle, and the valve timing (timing at which the maximum lift amount can be obtained) of the intake valve 2 variable. When the variable valve mechanism 6 is pressed by the nose 4b of the rotating intake cam 4a, the pressing force at that time is transmitted to the intake valve 2 via the variable valve mechanism 6 and the rocker arm 7, and the intake valve 2 Will lift.

  In the rocker arm 7, a base end portion is supported by a lash adjuster 8 and a tip end portion contacts the intake valve 2, and a roller 10 that receives pressure from the nose 4 b of the intake cam 4 a between the base end portion and the tip end portion. Is rotatably supported. The rocker arm 7 is biased toward the variable valve mechanism 6 by a lash adjuster 8 and a valve spring 9 of the intake valve 2. Accordingly, the intake valve 4 is pressed by the rotating intake cam 4a toward the intake valve 2 side by the rotating intake cam 4a, and the intake valve 2 is pressed by the valve spring 9 toward the rocker arm 7 side based on the rotation of the intake cam 4a. The valve 2 opens and closes.

Next, a specific structure of the variable valve mechanism 6 will be described.
The variable valve mechanism 6 is pushed by the rotating intake cam 4a and swings around the shaft 11, and through the swing, the mediating member 12 presses the intake valve 2 (rocker arm 7) in the valve opening direction, and the shaft. 11 and a drive mechanism 13 for translating the intermediate member 11 together with the mediating member 12 in the radial direction.

  The intermediary member 12 is connected to the shaft 11 extending in parallel with the intake camshaft 4 in a state enabling swinging around the shaft 11 and the first link 12a to the first link 12a. The second link 12b is connected through a pin 14 extending in parallel with the shaft 11 so as to be rotatable around the pin 14. The second link 12b is formed with a profile surface 16 that presses the intake valve 2 (rocker arm 7) in the valve opening direction while rotatably supporting a roller 27 that contacts the intake cam 4a. Further, the portion of the roller 27 of the second link 12b that comes into contact with the intake cam 4a is a cam side contact portion 15.

  The drive mechanism 13 includes a worm wheel 17 that is rotatable around a center line parallel to the intake camshaft 4. The shaft 11 is fixed at a position away from the center line of the worm wheel 17, and the first displacement end position P <b> 1 and the second displacement end position P <b> 2 of the shaft 11 are rotated through the rotation of the worm wheel 17. Displacement between them is performed. 1 and 2 show a state where the shaft 11 is located at the first displacement end position P1, and FIGS. 3 and 4 show a state where the shaft 11 is located at the second displacement end position P2. It is shown.

  The worm wheels 17 of the cylinders are connected to each other via a drive shaft 18 extending in parallel with the intake camshaft 4 over the cylinders. More specifically, a worm gear 19 is formed in a portion corresponding to the worm wheel 17 of each cylinder in the drive shaft 18, and the worm gear 19 is meshed with a gear 17 a formed on the outer periphery of the corresponding worm wheel 17. The worm wheels 17 are connected to each other via a drive shaft 18. A motor 20 is connected to the drive shaft 18. When the motor 20 is driven to rotate the drive shaft 18 in the forward direction or the reverse direction, the worm wheel 17 of each cylinder rotates integrally, and the shaft 11 of each cylinder fixed to the worm wheel 17. Are translated in parallel between the first displacement end position P1 and the second displacement end position P2.

  Here, the first displacement end position P1 is set to a position where the following (a) and (b) can be realized, and the second displacement end position P2 realizes the following (c) and (d). It is set to a possible position.

  (A) As shown in FIG. 1, when the cam side contact portion 15 of the second link 12b is in contact with the base circle portion 4c of the intake cam 4a, the first link 12a and the second link 12b are extended. At the same time, the cam side contact portion 15 of the second link 12b comes into contact with the intake cam 4a at the rear side (advance side) of the rotation direction.

  (B) As shown in FIG. 2, based on the fact that the cam side contact portion 15 of the second link 12b is pushed by the nose 4b of the intake cam 4a, the connecting portion between the first link 12a and the second link 12b is the intake air. The first and second links 12a and 12b are bent so as to protrude in the direction opposite to the direction in which the intake valve 2 is pressed by the cam 4a (upper right direction in the figure).

  (C) As shown in FIG. 3, when the cam side contact portion 15 of the second link 12b is in contact with the base circle portion 4c of the intake cam 4a, the connecting portion between the first link 12a and the second link 12b. The first and second links 12a and 12b bend so that the nose 4b of the intake cam 4a protrudes in the pressing direction of the intake valve 2 (lower left direction in the figure). Further, at this time, the cam side contact portion 15 contacts the intake cam 4a at the front side (retard side) in the rotational direction.

  (D) As shown in FIG. 4, when the cam side contact portion 15 of the second link 12b is positioned at the apex of the nose 4b of the intake cam 4a, the first link 12a and the second link 12b are extended. It becomes a state.

  As for the profile surface 16 of the second link 12b, when the shaft 11 is at the second displacement end position P2 (FIGS. 3 and 4), the cam side contact portion 15 and the profile surface 16 are in contact with the intake valve 2 side. The distance X in the opening / closing direction of the intake valve 2 with respect to the valve side contact portion 21 which is a portion is formed to be the maximum. Further, the profile surface 16 is formed such that the distance X becomes shorter as the shaft 11 approaches the first displacement end position P1 from the second displacement end position P2, and the shaft 11 has the first displacement end position P1. (FIGS. 1 and 2), the distance X is formed to be a minimum value.

  For example, in a situation where the engine operating state changes from high load operation to idle operation, the change indicated by the arrow Y2 in FIG. 14, which is an ideal change in the opening / closing characteristics of the intake valve 2, is realized. The shaft 11 is displaced from the state at the second displacement end position P2 to the first displacement end position P1 with the intention of doing so. Specifically, the worm wheel 17 is rotated through the drive of the motor 20 so that the shaft 11 is displaced from the state at the second displacement end position P2 to the first displacement end position P1. As a result, an ideal change in the opening / closing characteristics of the intake valve 2 under the above-described situation, that is, a change indicated by an arrow Y2 in FIG. 14 is realized.

  Next, a detailed structure around the shaft 11 fixed to the worm wheel 17, more specifically, a detailed structure of an adjusting mechanism for finely adjusting the radial position of the shaft 11 for each cylinder will be described with reference to FIGS. 5 and 6. Will be described with reference to the above. 5 is an enlarged view showing the structure around the shaft 11, and FIG. 6 is a cross-sectional view of the shaft 11 and the worm wheel 17 shown in FIG. 5 as viewed from the direction of arrow AA.

  As shown in FIG. 6, the shaft 11 is inserted into the small diameter portion 11 a inserted into the hole 22 of the worm wheel 17 and the hole 23 of the first link 12 a and has a larger diameter than the small diameter portion 11 a. And a large diameter portion 11b. The small-diameter portion 11a and the large-diameter portion 11b are formed such that the center lines C1 and C2 are shifted in parallel. In the shaft 11, the center line C2 of the large diameter portion 11b coincides with the center line of the hole 23 in the first link 12a, and the center line C1 of the small diameter portion 11a coincides with the center line of the hole 22 in the worm wheel 17. Yes. The large-diameter portion 11b and the hole 23 are relatively movable in the circumferential direction thereof, and the small-diameter portion 11a and the hole 22 are relatively movable in the circumferential direction thereof.

  Accordingly, the shaft 11 can be rotated around the center line C1 of the small diameter portion 11a with respect to the worm wheel 17, and the large diameter portion 11b is in contact with the hole 23 of the first link 12a through the rotation. It is possible to displace the worm wheel 17 around the center line C1 while relatively moving in the circumferential direction. Through the displacement of the large diameter portion 11 b around the center line C <b> 1, the first link 12 a (mediating member 12) is displaced in the radial direction of the shaft 11 with respect to the worm wheel 17. The large diameter portion 11b of the shaft 11 is displaced with respect to the worm wheel 17 around the center line C1 for each cylinder, whereby the shaft 11 and the shaft 11 of the first link 12a (mediating member 12) with respect to the worm wheel 17 are aligned. It is possible to adjust the position in the radial direction of each cylinder.

  In the large diameter portion 11b of the shaft 11, a long hole 25 for inserting a bolt 24 penetrating the large diameter portion 11b in the direction of the center line C2 is formed. As shown in FIG. 5, the long hole 25 extends in the circumferential direction around the center line C1 of the small diameter portion 11a, and the bolt 24 inserted into the long hole 25 is connected to the worm wheel 17 as shown in FIG. Screwed into. Then, by tightening the bolt 24 and sandwiching the large diameter portion 11b between the head 24a of the bolt 24 and the worm wheel 17, the circumference around the center line C1 with respect to the worm wheel 17 of the large diameter portion 11b. Displacement in the direction is prohibited. Normally, the displacement of the large diameter portion 11b with respect to the worm wheel 17 is prohibited in this manner. Accordingly, the fine adjustment of the position of the shaft 11 and the first link 12a (mediating member 12) in the radial direction of the shaft 11 with respect to the worm wheel 17 can be performed by loosening the bolt 24, and the bolt 24 is loosened. Will be done in the state.

  In this embodiment, an adjustment mechanism 26 for finely adjusting the radial position of the shaft 11 for each cylinder is configured by the small diameter portion 11a, the large diameter portion 11b, the bolt 24, the long hole 25, and the like in the shaft 11. Yes. The adjusting mechanism 26 is provided for each cylinder.

Next, the operation of the variable valve mechanism 6 will be described in detail.
As shown in FIG. 1, for example, the cam side contact portion 15 of the second link 12 b is in contact with the base circle portion 4 c of the intake cam 4 a, and the worm wheel 17 of each cylinder is driven through the drive of the motor 20. It is assumed that the shaft 11 is displaced between the first displacement end position P1 (FIG. 1) and the second displacement end position P2 (FIG. 2) by the rotation. In this case, the shaft 11 of each cylinder is similarly displaced between the first displacement end position P1 and the second displacement end position P2, and the cam side contact portion 15 is similarly intake cylinder 4a in each cylinder. The base circle portion 4c is displaced between a portion on the front side in the rotation direction and a portion on the rear side in the rotation direction.

  More specifically, when the shaft 11 is at the first displacement end position P1, the cam side contact portion 15 is located behind the base circle portion 4c shown in FIG. 1 in the rotational direction (the direction of the arrow AR1 in the drawing). Touch the part. In this case, when the intake valve 2 is lifted via the second link 12b by the nose 4b of the intake cam 4a, the valve timing of the intake valve 2 (timing at which the maximum lift is obtained) is most advanced. Further, when the shaft 11 is at the first displacement end position P1, the distance X in the opening and closing direction of the intake valve 2 between the cam side contact portion 15 and the valve side contact portion 21 is minimized. When the intake valve 2 is lifted, the maximum lift amount and operating angle of the valve 2 are minimized.

  On the other hand, as shown in FIG. 3, when the shaft 11 is at the second displacement end position P2, the cam side contact portion 15 is in front of the base circle portion 4c in the rotational direction (direction of arrow AR1 in the figure). Touch the part. In this case, when the intake valve 2 is lifted via the second link 12b by the nose 4b of the intake cam 4a, the valve timing of the intake valve 2 (timing at which the maximum lift is obtained) is most retarded. Further, when the shaft 11 is at the second displacement end position P2, the distance X in the opening / closing direction of the intake valve 2 between the cam side contact portion 15 and the valve side contact portion 21 is maximized. The maximum lift amount and operating angle of the valve 2 when the intake valve 2 is lifted are maximized.

  When the engine operating state changes from the high load operation to the idle operation, the shaft 11 of each cylinder moves from the second displacement end position P2 (FIGS. 3 and 4) to the first displacement end position P1 (FIG. 3). 1 and 2) simultaneously and in the same manner. As a result, the maximum lift amount and the operating angle of the intake valve 2 of each cylinder gradually change from the maximum value to the minimum value, and the valve timing of the intake valve 2 also advances from the most retarded state along with the change. It gradually changes to a horn state. As a result, an ideal change in the opening / closing characteristics of the intake valve 2 indicated by the arrow Y2 in FIG. 14 is realized in each cylinder.

  Here, when the cam side contact portion 15 is in contact with the base circle portion 4c of the intake cam 4a, the shaft 11 is moved to the first displacement end position P1 (FIG. 1) and the second displacement end position P2 (FIG. 3). ), The positional relationship between the first link 12a and the second link 12b changes between the state shown in (a) and the state shown in (c). More specifically, the first link 12a between the state in which the first and second links 12a and 12b shown in FIG. 1 are extended and the state in which the first and second links 12a and 12b shown in FIG. 3 are bent. And the positional relationship between the second link 12b and the second link 12b change. Thus, when the positional relationship between the first link 12a and the second link 12b is changed, the two are bent, so that the shaft 11 is displaced between the first displacement end position P1 and the second displacement end position P2. The space used for the displacement of the first and second links 12a and 12b when doing so is kept small.

  On the other hand, when the positional relationship between the first link 12a and the second link 12b is in an extended state as shown in (a) above (FIG. 1), the cam side contact portion 15 of the second link 12b is inhaled. When pushed by the nose 4b of the cam 4a, the positional relationship between the first link 12a and the second link 12b is bent as shown in (b) above (FIG. 2). Further, when the positional relationship between the first link 12a and the second link 12b is in a bent state as shown in (c) above (FIG. 3), the cam side contact portion 15 is the nose 4b of the intake cam 4a. As shown in FIG. 4, the bent state is maintained until the cam side contact portion 15 comes into contact with the apex of the nose 4b as shown in FIG. Thus, when the cam side contact portion 15 is pushed by the nose 4b, the first link 12a and the second link 12b are bent, so that the cam side contact portion 15 is pushed by the nose 4b. The space used for the displacement of the first and second links 12a and 12b is also kept small.

  As described above, whether the cam side contact portion 15 is pushed by the nose 4b of the intake cam 4a or not, the shaft 11 is moved between the first displacement end position P1 and the second displacement end position P2. It is possible to reduce the space used for the displacement of the first and second links 12a and 12b when the displacement is performed between the first and second links 12a and 12b. Therefore, even if the variable range of the valve timing is widened so that the advance timing of the valve timing of the intake valve 2 during idling is sufficient to reduce the pumping loss of the engine, the first and second links Occurrence of a space problem for displacing 12a and 12b is suppressed. That is, when the shaft 11 is displaced between the first displacement end position P1 and the second displacement end position P2, the first and second links 12a and 12b are secured on the engine as a space for the displacement. It is suppressed that it protrudes from the space.

  By the way, in a multi-cylinder engine, the opening / closing characteristics of the intake valve 2 vary among cylinders due to dimensional tolerances of the intake valve 2 and its peripheral components. However, variation in the opening / closing characteristics of the intake valve 2 among the cylinders cannot be eliminated through the rotation of the drive shaft 18 by the motor 20. This is because the adjustment of the opening / closing characteristics of the intake valve 2 through the rotation of the drive shaft 18 can be performed only in the same manner in each cylinder. Therefore, when the opening / closing characteristics of the intake valve 2 are adjusted in this way, the opening / closing characteristics of the intake valve 2 can be properly adjusted in a predetermined cylinder, but the opening / closing characteristics of the intake valve 2 are appropriate in other cylinders. Therefore, the opening / closing characteristics become inappropriate.

As a countermeasure to this, fine adjustment of the radial position of the shaft 11 is performed by the adjusting mechanism 26 provided for each cylinder.
Specifically, the bolt 24 shown in FIGS. 5 and 6 is loosened so that the large diameter portion 11b of the shaft 11 is rotatable with respect to the worm wheel 17 around the center line C1 of the small diameter portion 11a. By rotating the large diameter portion 11b around the center line C1 with respect to the worm wheel 17, the position of the shaft 11 and the mediating member 12 in the radial direction of the shaft 11 is finely adjusted. Open / close characteristics change. Therefore, the radial position of the shaft 11 is finely adjusted so that the opening / closing characteristics of the intake valve 2 are appropriate through the rotation of the large diameter portion 11b around the center line C1 with respect to the worm wheel 17. After the fine adjustment, the bolt 24 is tightened, and the rotation of the large diameter portion 11b around the center line C1 with respect to the worm wheel 17 is prohibited. Further, such fine adjustment of the radial position of the shaft 11 is performed for each cylinder, and the opening / closing characteristics of the intake valve 2 are adjusted to be appropriate for each cylinder. In this way, fine adjustment of the radial position of the shaft 11 is performed in each cylinder, so that the opening / closing characteristics of the intake valve 2 do not vary between the cylinders.

According to the embodiment described in detail above, the following effects can be obtained.
(1) It is possible to reduce the space used for the displacement of the first and second links 12a and 12b when the shaft 11 is displaced between the first displacement end position P1 and the second displacement end position P2. become. Therefore, even if the variable range of the valve timing is widened so that the advance timing of the valve timing of the intake valve 2 during idling is sufficient to reduce the pumping loss of the engine, the first and second links Occurrence of a space problem for displacing 12a and 12b is suppressed. Therefore, the range in which the valve timing of the intake valve 2 can be made variable does not have to be kept small, and the advance timing of the valve timing can be implemented to the sufficient degree described above. In other words, the opening / closing characteristics of the intake valve 2 can be varied over a wide range as required.

  (2) Through the integral translation of the shaft 11 of each cylinder by the drive mechanism 13, all the mediating members 12 of each cylinder are translated simultaneously in the radial direction of the shaft 11, and the opening / closing characteristics of the intake valve 2 can be varied. It is performed in the cylinder at the same time and in the same manner. When the opening / closing characteristics of the intake valve 2 vary among cylinders due to the crossing of the dimensions of the intake valve 2 and its peripheral components, the adjustment mechanism 26 provided for each cylinder is used to adjust the shaft 11 of each cylinder. The radial position is finely adjusted individually, whereby the variation in the opening / closing characteristics of the intake valve 2 among the cylinders can be eliminated.

  (3) With the rotation of the intake cam 4a, the positional relationship between the first link 12a and the second link 12b in the mediating member 12 is shown in FIG. 1 and FIG. It changes between the folded state of each other. Thus, by changing the positional relationship between the first link 12a and the second link 12b, the degree of freedom in forming the profile surface 16 in the second link 12b is increased, and the shaft 11 is moved from the first displacement end position P1 to the first link 12b. It is easy to form the profile surface 16 so that the opening / closing characteristics of the intake valve 2 change ideally when changing between the two displacement end positions P2.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 7, the variable valve mechanism 6 of this embodiment is also pushed by the rotating intake cam 4a and swings around the shaft 11, and the intake valve 2 (rocker arm 7) is opened through the swing. A mediating member 12 that presses in the direction and a drive mechanism 13 that translates the shaft 11 together with the mediating member 12 in the radial direction are provided.

  The intermediate member 12 is provided with a roller 27, a profile surface 16 and the like, and a contact portion of the roller 27 with the intake cam 4a side becomes a cam side contact portion 15 and an intake valve 2 side of the profile surface 16 ( A contact portion with the rocker arm 7) is a valve side contact portion 21.

  The drive mechanism 13 includes a drive shaft 18 that extends in parallel with the intake camshaft 4 over each cylinder of the engine. The shaft 11 of each cylinder is fixed to the drive shaft 18, and the fixed position of the drive shaft 18 on the shaft 11 is shifted from the center line C3 of the shaft 11. When the drive shaft 18 is rotated in the forward rotation direction or the reverse rotation direction through driving of the motor 20 connected to the drive shaft 18, the shaft 11 of each cylinder is integrally formed around the center line C4 of the drive shaft 18. Rotate. As a result, the shaft 11 of each cylinder is displaced between the first displacement end position P1 and the second displacement end position P2. 7 and 8 show a state where the shaft 11 is located at the first displacement end position P1, and FIGS. 9 and 10 show a state where the shaft 11 is located at the second displacement end position P2. It is shown.

  Here, regarding the first displacement end position P1, when the cam-side contact portion 15 is in contact with the base circle portion 4c of the intake cam 4a, the contact is in the rotational direction (arrow AR direction) with respect to the intake cam 4a. It is set to be performed at the rear side (advance side). Regarding the second displacement end position P2, when the cam side contact portion 15 is in contact with the base circle portion 4c of the intake cam 4a, the contact is in the rotational direction (arrow AR direction) with respect to the intake cam 4a. It is set to be performed at the front side (retard side) portion.

  Further, with respect to the profile surface 16 of the mediating member 12, when the shaft 11 is at the second displacement end position P2 (FIGS. 9 and 10), the intake valve 2 between the cam side contact portion 15 and the valve side contact portion 21 is used. The distance X in the opening / closing direction is maximized. Further, the profile surface 16 is formed such that the distance X becomes shorter as the shaft 11 approaches the first displacement end position P1 from the second displacement end position P2, and the shaft 11 has the first displacement end position P1. (FIGS. 7 and 8), the distance X is formed to be the minimum value.

  Then, for example, in a situation where the engine operating state changes from high load operation to idle operation, the shaft 11 is displaced from the state at the second displacement end position P2 to the first displacement end position P1. Thus, the drive shaft 18 is rotated through the drive of the motor 20.

  Next, a detailed structure of the shaft 11 around the drive shaft 18, more specifically, a detailed structure of the adjusting mechanism 26 for finely adjusting the radial position of the shaft 11 for each cylinder will be described with reference to FIGS. The description will be given with reference. 11 is an enlarged view showing a structure around the drive shaft 18 in the shaft 11, and FIG. 12 is a cross-sectional view of the shaft 11 and the drive shaft 18 shown in FIG.

  As shown in FIG. 11, an adjustment cam 31 formed in a disk shape having a smaller diameter than the shaft 11 is fixed to the drive shaft 18. The adjustment cam 31 and the drive shaft 18 are positioned such that the center lines C5 and C4 are shifted and parallel to each other. The center lines C5 and C4 are also parallel to the center line C3 of the shaft 11.

  As shown in FIG. 12, in the shaft 11, a hole 32 for penetrating the drive shaft 18 and a hole 33 for inserting the adjustment cam 31 are formed, and the center line of the hole 32 is the drive shaft 18. The center line of the hole 33 coincides with the center line C5 of the adjustment cam 31. The drive shaft 18 and the hole 32 are relatively movable in the circumferential direction around the center line C4, and the adjustment cam 31 and the hole 33 are located in the circumferential direction around the center line C5. Relative movement is possible.

  Accordingly, the shaft 11 can be rotated around the center line C5 of the adjustment cam 31 with respect to the drive shaft 18 (adjustment cam 31) shown in FIG. The shaft 11 is displaced in the radial direction while relatively moving in the direction. Then, by rotating the shaft 11 about the center line C5 with respect to the adjustment cam 31 for each cylinder, the radial direction of the shaft 11 with respect to the adjustment cam 31 (drive shaft 18) of the shaft 11 and the mediating member 12 is increased. Position adjustment can be performed for each cylinder.

  The adjustment cam 31 is formed with a long hole 25 for inserting a bolt 24 penetrating the cam 31 in the direction of the center line C5. The long hole 25 extends in the circumferential direction about the center line C5 of the adjustment cam 31, and the bolt 24 inserted into the long hole 25 is screwed into the shaft 11 as shown in FIG. Then, by tightening the bolt 24 and sandwiching the adjustment cam 31 between the head 24a of the bolt 24 and the shaft 11, the displacement of the shaft 11 in the circumferential direction with respect to the adjustment cam 31 around the center line C5. Is prohibited. Normally, the displacement of the shaft 11 relative to the adjustment cam 31 is prohibited in this way. Therefore, the fine adjustment of the position of the shaft 11 and the intermediate member 12 in the radial direction of the shaft 11 with respect to the adjustment cam 31 can be performed by loosening the bolt 24 and is performed with the bolt 24 loosened. Become.

  In this embodiment, an adjustment mechanism 26 for finely adjusting the radial position of the shaft 11 for each cylinder is configured by the adjustment cam 31, the bolt 24, the long hole 25, and the like on the drive shaft 18. The adjusting mechanism 26 is provided for each cylinder.

  By the way, as described in the first embodiment, in the multi-cylinder engine, the opening / closing characteristics of the intake valve 2 vary among cylinders due to dimensional tolerances of the intake valve 2 and its peripheral parts. As a countermeasure for this, also in this embodiment, fine adjustment of the radial position of the shaft 11 is performed by the adjusting mechanism 26 provided for each cylinder.

  Specifically, the bolt 24 shown in FIG. 11 and FIG. 12 is loosened so that the shaft 11 can rotate about the center line C <b> 5 of the cam 31 with respect to the adjustment cam 31. By rotating the shaft 11 about the center line C5 with respect to the adjustment cam 31, the position of the shaft 11 and the intermediate member 12 in the radial direction of the shaft 11 is finely adjusted, and accordingly the opening / closing characteristics of the intake valve 2 are adjusted. Changes. Therefore, the radial position of the shaft 11 is finely adjusted so that the opening / closing characteristics of the intake valve 2 are appropriate through the rotation of the shaft 11 around the center line C5 with respect to the adjustment cam 31. After the fine adjustment, the bolt 24 is tightened, and the rotation of the shaft 11 around the center line C5 with respect to the adjustment cam 31 is prohibited. Further, such fine adjustment of the shaft 11 is performed for each cylinder, and the opening / closing characteristics of the intake valve 2 are adjusted to be appropriate for each cylinder. In this way, fine adjustment of the radial position of the shaft 11 is performed in each cylinder, so that the opening / closing characteristics of the intake valve 2 do not vary between the cylinders.

According to this embodiment, an effect equivalent to the effect (2) described in the first embodiment can be obtained.
[Other Embodiments]
In addition, each said embodiment can also be changed as follows, for example.

  -In 1st and 2nd embodiment, although the drive mechanism 13 which displaces the shaft 11 to radial direction through rotation operation was illustrated, this invention is not limited to this. For example, a driving mechanism that slides the shaft 11 in the radial direction may be employed.

  In the first and second embodiments, the adjustment mechanism 26 that performs the fine adjustment through the rotation operation of the shaft 11 is illustrated as an adjustment mechanism that can finely adjust the radial position of the shaft 11 of each cylinder individually. The present invention is not limited to this. For example, an adjustment mechanism of a method in which the shaft 11 is individually slid in the radial direction for each cylinder may be employed.

In the first embodiment, the adjustment mechanism 26 is not necessarily provided.
-In 2nd Embodiment, you may comprise the mediation member 12 by the 1st link and the 2nd link like 1st Embodiment.

Schematic which shows the structure of the variable valve mechanism of 1st Embodiment. Schematic which shows operation | movement of the variable valve mechanism. Schematic which shows operation | movement of the variable valve mechanism. Schematic which shows operation | movement of the variable valve mechanism. The enlarged view which shows the structure around the shaft of a variable valve mechanism. Sectional view of the shaft, worm wheel, etc. of FIG. Schematic which shows the structure of the variable valve mechanism of 2nd Embodiment. Schematic which shows operation | movement of the variable valve mechanism. Schematic which shows operation | movement of the variable valve mechanism. Schematic which shows operation | movement of the variable valve mechanism. The enlarged view which shows the structure around the drive shaft in the shaft of a variable valve mechanism. Sectional drawing which looked at the shaft of FIG. 11, a drive shaft, etc. from the arrow BB direction. The timing chart which shows the transition (valve opening / closing characteristic) of the lift amount of an intake valve and an exhaust valve with respect to the change of a crank angle. The timing chart which shows the transition (valve opening / closing characteristic) of the lift amount of an intake valve and an exhaust valve with respect to the change of a crank angle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Intake valve, 4 ... Intake cam shaft, 4a ... Intake cam, 4b ... Nose, 4c ... Base circle part, 6 ... Variable valve mechanism, 7 ... Rocker arm, 8 ... Rush adjuster, 9 ... Valve Spring, 10 ... Roller, 11 ... Shaft, 11a ... Small diameter part, 11b ... Large diameter part, 12 ... Intermediary member, 12a ... First link, 12b ... Second link, 13 ... Drive mechanism, 14 ... Pin, 15 ... Cam Side contact portion, 16 ... profile surface, 17 ... worm wheel, 17a ... gear, 18 ... drive shaft, 19 ... worm gear, 20 ... motor, 21 ... valve side contact portion, 22 ... hole, 23 ... hole, 24 ... bolt, 24a ... head, 25 ... long hole, 26 ... adjustment mechanism, 27 ... roller, 31 ... adjustment cam, 32 ... hole, 33 ... hole.

Claims (4)

An intermediate member that is pushed by the rotating cam and swings around the shaft and presses the intake valve in the valve opening direction through the swing, and a cam side contact portion that is a contact portion of the intermediate member with the cam side are the same. A drive mechanism that translates the shaft in a radial direction together with the intermediate member so as to be displaced forward or backward in the rotational direction of the cam, and the intermediate member has a profile surface that presses the intake valve in the valve opening direction. With respect to this profile surface, the distance in the opening and closing direction of the intake valve between the valve side contact portion that is a contact portion with the intake valve side and the cam side contact portion is parallel to the shaft by the drive mechanism. In a variable valve mechanism of an internal combustion engine that is configured to change with movement,
The intermediary member is connected to the shaft so as to be rotatable about the same pin via a first link that can swing around the shaft and a pin that extends in the same direction as the shaft relative to the first link. And the cam side contact portion and the second link on which the profile surface is formed,
The drive mechanism displaces the shaft between a first displacement end position and a second displacement end position;
The first displacement end position is set to a position where the following (a) and (b) can be realized, and the second displacement end position is a position where the following (c) and (d) can be realized. Set to
(A) When the cam side contact portion is in contact with the base circle portion of the cam, the first link and the second link are extended, and the cam side contact portion of the second link is (B) Based on the fact that the cam side contact portion is pushed by the nose of the cam, the connecting portion between the first link and the second link is the cam. The first and second links bend so as to protrude in a direction opposite to the direction of the intake valve pressing by (c) When the cam side contact portion is in contact with the base circle portion of the cam, The first and second links are bent so that the connecting portion with the second link protrudes in the pressing direction of the intake valve due to the nose of the cam, and the cam side contact portion rotates with respect to the cam. (D) When the cam side contact portion is positioned at the nose apex portion of the cam, the first link and the second link are in an extended state. The second link When the shaft is at the second displacement end position, the distance in the opening / closing direction of the intake valve between the cam side contact portion and the valve side contact portion is maximum, and the shaft is in the second position. A variable valve mechanism for an internal combustion engine, characterized in that the distance decreases as the distance from the displacement end position approaches the first displacement end position. The shaft, the first link, the pin, and the second link are provided for each cylinder of the internal combustion engine, and the drive mechanism integrally translates the shaft of each cylinder,
The variable valve mechanism for an internal combustion engine according to claim 1, wherein the shaft of each cylinder can be finely adjusted individually by an adjusting mechanism provided for each cylinder in the radial direction. An intermediate member that is pushed by the rotating cam and swings around the shaft and presses the intake valve in the valve opening direction through the swing, and a cam side contact portion that is a contact portion of the intermediate member with the cam side are the same. A drive mechanism that translates the shaft in a radial direction so that the shaft is displaced forward or backward in the rotational direction of the cam, and a profile surface that contacts the mediation member is formed on the mediation member. A distance in the opening / closing direction of the intake valve between the valve side contact portion, which is a contact portion with the valve side, and the cam side contact portion is changed with the parallel movement of the shaft by the drive mechanism. In the variable valve mechanism of the internal combustion engine,
The drive mechanism integrally displaces the shaft provided for each cylinder of the internal combustion engine between a first displacement end position and a second displacement end position;
The first displacement end position is set such that when the cam side contact portion is in contact with the base circle portion of the cam, the contact is made at the portion on the rear side in the rotational direction with respect to the cam. And
The second displacement end position is set so that when the cam side contact portion is in contact with the base circle portion of the cam, the contact is made at the portion on the front side in the rotational direction with respect to the cam. And
Regarding the profile surface of the mediating member, when the shaft position is at the second displacement end position, the distance in the opening / closing direction of the intake valve between the cam side contact portion and the valve side contact portion is maximized, and the shaft The distance is shortened as the position approaches the first displacement end position from the second displacement end position,
A variable valve mechanism for an internal combustion engine, wherein the shaft of each cylinder can be finely adjusted individually by an adjusting mechanism provided for each cylinder in the radial direction. The variable valve for an internal combustion engine according to claim 2 or 3, wherein the adjustment mechanism adjusts a radial position of the shaft by rotating the shaft around a center line parallel to the axis of the shaft. mechanism.

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