JP2008025441A - Variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear capable of varying open and close characteristics of an engine valve without using complicated components. <P>SOLUTION: The variable valve gear 6 is provided with only an input link 13, an auxiliary link 14 and an output link 15 and the like as a mechanism opening and closing an intake valve 2, and complicated components are not used as components for the mechanism. Also, open and close characteristics of the intake valve 2 can be varied by changing a position of a cam side contact part 18 in the input link 13 and a distance X in the open and close direction of the intake valve 2 between a valve side contact part 21 of a profile surface 20 and the cam side contact part 18 through displacement in the radial direction of a first shaft 11. Since a function required for a drive mechanism 22 at minimum is only displacing the first shaft 11 in the radial direction, complicated components are not necessary to be used in the mechanism 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism that makes an opening / closing characteristic of an engine valve of an internal combustion engine variable.

  An internal combustion engine such as an automobile engine has been proposed in which the opening / closing characteristics of an engine valve such as an intake valve or an exhaust valve are variable according to the engine operating state. For example, in the internal combustion engine of Patent Document 1, a variable valve lift mechanism is provided as a variable valve mechanism that makes the maximum lift amount and operating angle of the intake valve variable, and the mechanism is driven according to the engine operating state. Yes.

  Here, the variable valve lift mechanism is an input arm that is pushed by the rotating intake cam and swings about the shaft, and swings about the shaft based on the swing of the input arm to lift the intake valve. An output arm and a slider which is disposed in a state of penetrating the arms and engaged with gears having different inclination directions of the tooth traces to both arms are provided. When the slider is displaced in the axial direction of the shaft, the relative position in the swing direction of the input arm and the output arm is changed by the action of the gear, and the maximum lift amount and the operating angle of the intake valve are increased or Changed to decrease.

  FIG. 4 shows the transition (opening / closing characteristics) of the lift amount of the intake valve and the exhaust valve with respect to the change of the crank angle. When the maximum lift amount and operating angle of the intake valve are changed by driving the variable valve lift mechanism, the opening / closing characteristics of the intake valve change as indicated by an arrow Y1 in the drawing. That is, the maximum lift amount and the operating angle of the intake valve change to the increase side or the decrease side while the valve timing of the intake valve (the timing at which the maximum lift amount is obtained) is constant.

  The maximum lift amount and operating angle of the intake valve are controlled, for example, as follows according to the engine operating state. That is, 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 during high load operation, the opening timing of the intake valve is advanced and the valve overlap between the intake valve and the exhaust valve becomes large, which adversely affects engine operation. There is a risk. 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 timing is changed to the advance side, the intake valve closing timing 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. However, only by driving the variable valve lift mechanism described above, only the maximum lift amount and operating angle of the intake valve can be made variable as shown in FIG. 4, and the valve timing of the intake valve (the maximum lift amount can be obtained). (Timing) cannot be changed.

  For this reason, as disclosed in Patent Document 1, it is conceivable to provide a variable valve timing mechanism as a variable valve mechanism that varies the valve timing of the intake valve separately from the variable valve lift mechanism. This variable valve timing mechanism transmits the rotation of the crankshaft, which is the output shaft of the internal combustion engine, to the intake camshaft to which the intake cam is fixed to rotate the same, and also rotates the relative rotation phase of the intake camshaft with respect to the crankshaft. Change to the advance side or retard side. By changing the relative rotation phase of the intake camshaft with respect to the crankshaft in this way, the valve timing of the intake valve is changed to the advance side or the retard side.

In a situation where the operating state of the internal combustion engine changes from high load operation to idle operation, a variable valve lift mechanism is provided so that an ideal change in the opening / closing characteristics of the intake valve indicated by the arrow Y2 in FIG. 5 can be obtained. Is driven as follows. That is, in addition to the control of the maximum lift amount and the operating angle of the intake valve based on the drive of the variable valve lift mechanism described above, the valve timing of the intake valve is set to the retard side of the most advanced angle state based on the drive of the variable valve lift mechanism. The state is controlled from the state to the most advanced angle state. As a result, the opening / closing characteristics of the intake valve change as shown by the arrow Y2 in FIG.
JP 2001-263015 A

When the variable valve mechanism of Patent Document 1 described above is used to change the opening / closing characteristics of the engine valve, the following problems [1] and [2] occur.
[1] In the variable valve lift mechanism (variable valve mechanism), gears are formed on the input arm, the output arm, and the slider, respectively, in order to make the relative positions of the input arm and the output arm swingable. The components of the Aircraft are complicated and the cost increases.

  [2] When the opening / closing characteristics of the intake valve are made variable, it is ideal that the opening / closing characteristics of the intake valve are made variable so that the valve timing is advanced as the maximum lift amount and the operating angle are reduced. However, in order to realize such variable opening / closing characteristics of the intake valve, it is necessary to provide a variable valve timing mechanism in addition to the variable valve lift mechanism, which requires extra work and cost to install it. Is inevitable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable valve mechanism that can vary the opening / closing characteristics of an engine valve without using complicated parts. .

  Another object of the present invention is to provide a variable valve mechanism that can ideally change the opening / closing characteristics of the intake valve without separately providing a mechanism for making the valve timing of the intake valve variable. There is.

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, in the variable valve mechanism that varies the opening and closing characteristics of the engine valve that opens and closes based on the rotation of the cam of the internal combustion engine, the first is achieved by pressing the rotating cam. An input link that swings around the shaft, an auxiliary link that is positioned closer to the engine valve than the first shaft and is parallel to the shaft, and swingable around the second shaft; The first pin extending in the same direction as the first shaft is connected to be pivotable about the pin, and the second pin extends in the same direction as the second shaft with respect to the auxiliary link. A profile surface is formed that is pivotally connected about a pin and has a profile surface that presses the engine valve in the valve opening direction when the input link swings based on the rotation of the cam. A link and a drive mechanism for displacing the first shaft in a radial direction, and a profile surface of the output link has a valve side contact portion that is a contact portion with the engine valve side, and the drive The cam side contact portion and the valve according to the position of the cam side contact portion when the cam side contact portion, which is the contact portion of the input link with the cam, is displaced through displacement of the first shaft by a mechanism. The gist is that the distance between the side contact portion and the opening and closing direction of the engine valve is changed.

  According to the above configuration, when the input link swings around the first shaft due to the rotation of the rotating cam, the output link reciprocates on a predetermined track, and the engine valve is pressed by the profile surface of the output link. Through this, the engine valve opens and closes. The opening / closing characteristics of the engine valve at this time vary depending on the position of the cam-side contact portion of the input link and the distance in the opening / closing direction of the engine valve between the cam-side contact portion and the valve-side contact portion of the profile surface. . These positions and distances are variable depending on the radial displacement of the first shaft by the drive mechanism. For this reason, the opening and closing characteristics of the engine valve are made variable by displacing the first shaft in the radial direction by the drive mechanism. Here, as a mechanism for opening and closing the engine valve, only links and the like are provided, and no complicated parts are used. Also, regarding the drive mechanism for making the opening / closing characteristics of the engine valve variable, the minimum function required for the engine is only to displace the first shaft in the radial direction. There is no need to use complex parts. Therefore, the opening / closing characteristics of the engine valve can be made variable without using complicated parts.

  According to a second aspect of the present invention, in the first aspect of the present invention, the engine valve is an intake valve, and the drive mechanism is configured such that the cam side contact portion of the input link has a front side and a rear side in the rotational direction of the cam. The first shaft is displaced so as to be displaced to the side, and the profile surface of the output link is configured such that the cam side contact portion is rearward in the rotational direction of the cam through the displacement of the first shaft by the drive mechanism. The gist of the present invention is that the distance between the cam side contact portion and the valve side contact portion in the opening / closing direction of the intake valve is shortened as the displacement is increased.

  According to the above configuration, the valve timing (the maximum lift amount of the intake valve) of the intake valve increases as the cam side contact portion of the input link is displaced rearward in the rotational direction of the cam through the radial displacement of the first shaft by the drive mechanism. The resulting timing is advanced. Further, as the cam side contact portion of the input link is displaced rearward in the rotational direction of the cam, the distance in the intake valve opening / closing direction between the cam side contact portion and the valve side contact portion on the profile surface of the output link becomes shorter. Thus, the maximum lift amount and operating angle of the intake valve are made small. Accordingly, an ideal intake valve is configured such that the valve timing of the intake valve advances as the maximum lift amount and operating angle of the intake valve are reduced only by the radial displacement of the first shaft by the drive mechanism. The opening / closing characteristics can be varied. Further, in order to realize such an ideal opening / closing characteristic of the intake valve, it is not necessary to separately provide a mechanism for changing the valve timing of the intake valve.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the drive mechanism rotates the shaft around a center line parallel to the axis of the first shaft, thereby the first mechanism. The shaft was displaced in the radial direction.

  According to the above configuration, the minimum function required for the drive mechanism to displace the first shaft in the radial direction is to rotate the shaft around a center line parallel to the axis of the first shaft. Therefore, it is not necessary to use complicated parts in the mechanism in order to provide the function.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, between the cam side contact portion in the input link and the valve side contact portion in the profile surface of the output link. An adjustment mechanism for displacing the second shaft in the radial direction is further provided so that the distance in the opening / closing direction of the engine valve is variable.

  When the first shaft is displaced to a predetermined position by the drive mechanism, the maximum lift amount and the operating angle of the engine valve are not necessarily values corresponding to the predetermined position. This is because the opening and closing direction of the engine valve between the cam side contact portion and the valve side contact portion when the first shaft is displaced to the predetermined position due to the dimensional tolerance of each component constituting the variable valve mechanism. This is because the distance about is deviated from an appropriate value. However, according to the above configuration, the second shaft can be displaced in the radial direction by the adjusting mechanism so that the deviation of the distance from the appropriate value is eliminated. More specifically, the movement range of the valve side contact portion on the cam profile surface at the time of opening and closing the engine valve is reduced in the radial direction of the second shaft so that the distance from the proper value of the distance is eliminated when the engine valve is opened and closed. It can be changed by displacement. As a result, the maximum lift amount and the operating angle of the engine valve can accurately correspond to the positions of the first shaft in the radial direction.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the adjusting mechanism rotates the shaft around a center line parallel to the axis of the second shaft, thereby rotating the second shaft. It was assumed to be displaced in the radial direction.

  According to the above configuration, the minimum function required for the adjustment mechanism to displace the second shaft in the radial direction is to rotate the shaft about a center line parallel to the axis of the second shaft. Therefore, it is not necessary to use complicated parts in the mechanism in order to provide the function.

Hereinafter, an embodiment in which the present invention is applied to an automobile engine will be described with reference to FIG.
FIG. 1 is a schematic view showing a structure around an intake valve and an exhaust valve in a cylinder head of an engine.

  The cylinder head 1 of the engine is provided with an intake valve 2 and an exhaust valve 3 as engine valves. Among these engine valves, the intake valve 2 opens and closes so as to connect and shut off the intake passage and the combustion chamber in the engine, and the exhaust valve 3 connects and shuts off the exhaust passage and the combustion chamber in the engine. It opens and closes as much as possible.

  Further, the cylinder head 1 is provided with an intake camshaft 4 and an exhaust camshaft 5 for driving the intake valve 2 and the exhaust valve 3. The intake camshaft 4 and the exhaust camshaft 5 are fixed with an intake cam 4a and an exhaust cam 5a, respectively, and rotate together with the intake cam 4a and the exhaust cam 5a through transmission of rotation from the crankshaft of the engine. The intake valve 2 and the exhaust valve 3 are opened and closed through the integral rotation of the intake cam 4a and the exhaust cam 5a with the intake cam shaft 4 and the exhaust cam shaft 5.

  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 cam 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, the base end is supported by the lash adjuster 8, the front end contacts the intake valve 2, and the roller 10 receives pressure from the cam nose 4 b of the intake cam 4 a between the base end and the front end. Is rotatably supported. The rocker arm 7 is biased toward the variable valve mechanism 6 by 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 includes a first shaft 11 and a second shaft 12 that extend parallel to the intake camshaft 4. Further, the mechanism 6 is configured to change the axis of the shaft 12 while sliding around the input link 13 and the second shaft 12 that can swing around the axis of the shaft 11 while sliding around the first shaft 11. An auxiliary link 14 that can swing in the center, and an input link 13 and an output link 15 connected to the auxiliary link 14 are also provided.

  The first shaft 11 is located on the side of the intake camshaft 4, and the input link 13 extends from the first shaft 11 between the intake cam 4 a and the rocker arm 7. The front end of the input link 13 and the output link 15 are connected to each other by a pin 16 extending in the same direction as the first shaft 11 so as to be rotatable around the pin 16. A roller 17 that contacts the intake cam 4a and is rotatable about the pin 16 is provided at the tip of the input link 13. In the input link 13, the roller 17 is in contact with the intake cam 4 a, and a portion of the roller 17 that is in contact with the intake cam 4 a side is a cam side contact portion 18 of the input link 13.

  The second shaft 12 is located on the side of the rocker arm 7, and the auxiliary link 14 extends from the second shaft 12 toward the output link 15. The tip end portion of the auxiliary link 14 and the end portion of the output link 15 on the auxiliary link 14 side are coupled to each other by a pin 19 extending in the same direction as the second shaft 12 so as to be rotatable about the pin 19. Further, the rocker arm 7 side surface of the output link 15 contacts the roller 10 of the rocker arm 7 when the intake cam 4a rotates, and the profile surface presses the intake valve 2 through the rocker arm 7 in the valve opening direction. It is 20. A portion of the profile surface 20 of the output link 15 that contacts the intake valve 2 side (more precisely, the roller 10 of the rocker arm 7) is a valve side contact portion 21.

  Therefore, in the variable valve mechanism 6, when the input link 13 is swung around the first shaft 11 by being pushed by the cam nose 4 b of the rotating intake cam 4 a, the auxiliary link connected via the input link 13 and the output link 15. The link 14 swings around the second shaft 12. The output link 15 connected to the input link 13 and the auxiliary link 14 reciprocates on a predetermined track as the input link 13 and the auxiliary link 14 swing. When the output link 15 reciprocates on the predetermined track, the intake valve 2 is pressed through the rocker arm 7 by the profile surface 20 of the output link 15, and the intake valve 2 is opened and closed through the pressing. Become. When the intake valve 2 is opened and closed, the valve-side contact portion 21 on the profile surface 20 reciprocates within a predetermined movement range H along the longitudinal direction of the output link 15.

  The opening / closing characteristics of the intake valve 2 include the position of the cam side contact portion 18 in the input link 13 in the rotational direction (arrow R direction) of the intake cam 4a, and the valve side contact portion of the cam side contact portion 18 and the output link 15. 21 and the distance X in the opening / closing direction of the intake valve 2 is determined. Therefore, by making the position and the distance X variable, the opening / closing characteristics of the intake valve 2, that is, the maximum lift amount, the operating angle, and the valve timing (timing at which the maximum lift amount can be obtained) can be made variable. Become.

Here, in the variable valve mechanism 6, the structure in which the position of the cam side contact portion 18 is variable and the structure in which the distance X is variable will be described individually.
[Structure that makes the position of the cam side contact portion 18 variable]
Changing the position of the cam-side contact portion 18 forward and backward in the rotational direction of the intake cam 4a causes the input link 13 and the roller 17 to move through the intake cam 4a through the displacement of the first shaft 11 in the radial direction by the drive mechanism 22. This is realized by displacing the rotation direction forward and backward.

  The drive mechanism 22 includes an eccentric shaft 23 that extends parallel to the axis of the first shaft 11 and is fixed to the shaft 11, and is rotatably supported on the cylinder head 1. The eccentric shaft 23 is connected to a motor 24, and rotates about the axis (center line) of the eccentric shaft 23 through driving of the motor 24. Therefore, when the eccentric shaft 23 is rotated by a predetermined angle through driving of the motor 24, the first shaft 11 is rotated about the axis of the eccentric shaft 23 and displaced in the radial direction. The locus of the axis of the first shaft 11 at this time is indicated by a two-dot chain line L1. As for the angular range in which the eccentric shaft 23 is rotated by the motor 24, the radial displacement of the first shaft 11 due to the rotation of the eccentric shaft 23 within the range sucks the position of the cam side contact portion 18. The cam 4a is set so that it can be changed forward and backward in the rotational direction.

  As described above, when the eccentric shaft 23 is rotated to displace the first shaft 11 in the radial direction so that the axis of the first shaft 11 is displaced toward the roller 17, the roller 17 moves forward in the rotational direction of the intake cam 4a. The position of the cam side contact portion 18 of the input link 13 changes forward in the rotational direction of the intake cam 4a. On the other hand, when the eccentric shaft 23 is rotated to displace the first shaft 11 in the radial direction so that the axis of the first shaft 11 is displaced to the side opposite to the roller 17, the roller 17 rotates the intake cam 4a. The position of the cam side contact portion 18 of the input link 13 is changed rearward in the rotational direction of the intake cam 4a.

[Structure with variable distance X]
Making the distance X variable is realized by setting a shape of the profile surface 20 of the output link 15 in the moving direction of the valve side contact portion 21.

  The profile surface 20 has the distance X according to the position of the cam side contact portion 18 when the cam side contact portion 18 of the input link 13 is displaced through the radial displacement of the first shaft 11 by the drive mechanism 22. Is formed to change. In other words, the shape of the profile surface 20 in the moving direction of the valve-side contact portion 21 is set so that the distance X changes according to the position of the cam-side contact portion 18 in the rotational direction of the intake cam 4a.

  More specifically, the valve-side contact portion 21 on the profile surface 20 moves in the moving range H during the opening / closing operation of the intake valve 2 as the position of the cam-side contact portion 18 changes forward in the rotational direction of the intake cam 4a (arrow R direction). The shape of the profile surface 20 is set so that the distance X when reciprocating is gradually increased. Further, as the position of the cam side contact portion 18 changes rearward in the rotation direction of the intake cam 4a (opposite to the arrow R), the valve side contact portion 21 on the profile surface 20 moves in the moving range H during the opening / closing operation of the intake valve 2. The shape of the profile surface 20 is also set so that the distance X when reciprocating within is gradually shortened.

Next, how the variable valve mechanism 6 changes the opening / closing characteristics of the intake valve 2 will be described with reference to FIGS.
As the axial line of the first shaft 11 is largely displaced in the radial direction toward the roller 17 through the rotation of the eccentric shaft 23, the roller 17 is displaced forward (in the direction of arrow R) of the intake cam 4a. As shown, the position of the cam side contact portion 18 of the input link 13 changes forward in the rotational direction of the intake cam 4a. Further, the more the input link 13 and the output link 15 are displaced so that the position of the cam side contact portion 18 changes greatly in the forward direction of the intake cam 4a, the intake air between the cam side contact portion 18 and the valve side contact portion 21 becomes larger. The distance X in the opening / closing direction of the valve 2 becomes longer. That is, the shape of the profile surface 20 in the output link 15 is set so that the distance X changes as described above. Accordingly, as the position of the cam side contact portion 18 is displaced forward in the rotational direction of the intake cam 4a, the valve timing of the intake valve 2 (the timing at which the maximum lift amount is obtained) is gradually retarded, and the distance As X gradually increases, the maximum lift amount and operating angle of the intake valve 2 gradually increase.

  Further, when the eccentric shaft 23 is rotated to displace the first shaft 11 in the radial direction so that the axis of the first shaft 11 is displaced to the side opposite to the roller 17 side, the roller 17 rotates the intake cam 4a. As shown in FIG. 3, the position of the cam side contact portion 18 of the input link 13 changes to the rear in the rotational direction of the intake cam 4a. Further, the more the input link 13 and the output link 15 are displaced so that the position of the cam side contact portion 18 greatly changes in the rearward direction of the intake cam 4a, the intake air between the cam side contact portion 18 and the valve side contact portion 21 becomes larger. The distance X in the opening / closing direction of the valve 2 is shortened. That is, the shape of the profile surface 20 in the output link 15 is set so that the distance X changes as described above. Accordingly, the valve timing of the intake valve 2 (the timing at which the maximum lift amount is obtained) gradually advances as the position of the cam side contact portion 18 is displaced rearward in the rotation direction of the intake cam 4a, and the above distance As X is gradually shortened, the maximum lift amount and operating angle of the intake valve 2 are gradually reduced.

  As described above, when the first shaft 11 is displaced in the radial direction so that the position of the cam side contact portion 18 changes forward and backward in the rotation direction of the intake cam 4a, the intake valve 2 as described above according to the change. The valve timing and the maximum lift amount and operating angle of the intake valve 2 change simultaneously. Therefore, the ideal opening / closing characteristics of the intake valve 2 as shown in FIG. 5 are realized, such that the valve timing of the valve 2 advances as the maximum lift amount and operating angle of the intake valve 2 become smaller. be able to.

  By the way, in the variable valve mechanism 6, when the first shaft 11 is displaced to a predetermined position through driving of the drive mechanism 22, the maximum lift amount and the operating angle of the intake valve 2 are not necessarily values corresponding to the predetermined position. Not necessarily. This is because the distance X deviates from an appropriate value when the first shaft 11 is displaced to the predetermined position due to a dimensional tolerance of each component constituting the variable valve mechanism 6. The variable valve mechanism 6 is provided with an adjustment mechanism 25 that performs adjustment to eliminate such a deviation from the appropriate value of the distance X. Hereinafter, a specific structure of the adjusting mechanism 25 will be described with reference to FIG.

  The adjustment mechanism 25 includes an eccentric shaft 26 that extends parallel to the axis of the second shaft 12 and is fixed to the shaft 12. The eccentric shaft 26 is rotatably supported by a support portion 27 provided on the cylinder head 1 and can be fixed in the rotational direction at an arbitrary rotational position. When the eccentric shaft 26 is unlocked and the eccentric shaft 26 is rotated by a predetermined angle about its axis (center line), the second shaft 12 is centered on the axis of the eccentric shaft 26. It will rotate and be displaced in the radial direction. The locus of the axis of the second shaft 12 at this time is indicated by a two-dot chain line L2.

  When the second shaft 12 is displaced in the radial direction, the output link 15 connected to the shaft 12 via the auxiliary link 14 is also displaced, and the positional relationship between the cam side contact portion 18 and the valve side contact portion 21 is displaced. Also changes. As a result, the distance X in the opening / closing direction of the intake valve 2 between the cam side contact portion 18 and the valve side contact portion 21 changes. More specifically, due to the displacement of the output link 15, the moving range H of the valve side contact portion 21 that reciprocates on the profile surface 20 during the opening / closing operation of the intake valve 2 changes in the moving direction of the valve side contact portion 21. Based on this, the distance X changes.

  Therefore, the second shaft 12 is rotated about the axis of the eccentric shaft 26 to be displaced in the radial direction so that the deviation from the appropriate value of the distance X described above is eliminated, and in this state, the rotational position of the eccentric shaft 26 is changed. By fixing, the maximum lift amount and the operating angle of the intake valve 2 can be made to correspond exactly to the position of the first shaft 11.

According to the embodiment described in detail above, the following effects can be obtained.
(1) In the variable valve mechanism 6, the input link 13 and the auxiliary link 14 swing around the first shaft 11 and the second shaft 12 through the pressing of the rotating intake cam 4 a, respectively. The output link 15 connected to the 13, 14 reciprocates on a predetermined track. When the output link 15 reciprocates on the predetermined track, the output link 15 presses the intake valve 2 via the rocker arm 7 to open and close the intake valve 2.

  The opening / closing characteristics of the intake valve 2 include the position of the cam side contact portion 18 of the input link 13 in the rotational direction of the intake cam 4a and the valve side contact of the cam side contact portion 18 and the profile surface 20 of the output link 15. It varies depending on the distance X with respect to the opening / closing direction of the intake valve 2 with respect to the portion 21. These positions and distances X are variable by rotating the first shaft 11 about the axis (center line) of the eccentric shaft 23 through driving of the drive mechanism 22 and displacing the shaft 11 in the radial direction. It is said. For this reason, the opening / closing characteristics of the intake valve 2 are made variable by driving the drive mechanism 22 to displace the first shaft 11 in the radial direction.

  Here, as a mechanism for opening and closing the intake valve 2, only the links 13 to 15 are provided, and no complicated parts are used. Further, regarding the drive mechanism 22 for making the opening / closing characteristics of the intake valve 2 variable, the minimum function required for the mechanism 22 is to displace the first shaft 11 in the radial direction, more specifically, the first shaft. 11 is merely rotated around the axis of the eccentric shaft 23, and therefore it is not necessary to use complicated parts for the mechanism 22 in order to provide the function. Therefore, the opening / closing characteristics of the intake valve 2 can be made variable without using complicated parts.

  (2) The position of the cam side contact portion 18 in the input link 13 is moved rearward in the rotational direction of the intake cam 4a through the radial displacement based on the rotation of the first shaft 11 around the eccentric shaft 23. The valve timing of the intake valve 2 (timing at which the maximum lift amount is obtained) is advanced. Further, as the position of the cam side contact portion 18 is moved rearward in the rotation direction of the intake cam 4a, the distance X in the opening / closing direction of the intake valve 2 between the cam side contact portion 18 and the valve side contact portion 21 increases. As a result, the maximum lift amount and operating angle of the intake valve 2 are reduced. Therefore, the valve timing of the valve 2 is advanced as the maximum lift amount and the operating angle of the intake valve 2 are reduced only by the rotation of the first shaft 11 around the eccentric shaft 23 by the drive mechanism 22. The ideal opening / closing characteristics of the intake valve 2 as shown in FIG. 5 can be changed. Further, in order to realize such a variable opening / closing characteristic of the ideal intake valve 2, it is not necessary to separately provide a mechanism for changing the valve timing of the intake valve 2 as described in the “Background Art” section. .

  (3) When the first shaft 11 is displaced to a predetermined position through the drive of the drive mechanism 22, the intake valve is caused by a deviation from the appropriate value of the distance X due to dimensional tolerance of each component constituting the variable valve mechanism 6. The maximum lift amount and operating angle of 2 may not be values corresponding to the predetermined position. In this case, the second shaft 12 is rotated around the eccentric shaft 26 and displaced in the radial direction by using the adjusting mechanism 25 so that the deviation from the appropriate value of the distance X described above is eliminated. The lift amount and the operating angle can accurately correspond to the position of the first shaft 11.

  (4) Since the minimum function required for the adjustment mechanism 25 to displace the second shaft 12 in the radial direction is only to rotate the second shaft 12 around the eccentric shaft 26, It is not necessary to use complicated parts for the mechanism 25 in order to have a function.

In addition, the said embodiment can also be changed as follows, for example.
As the adjusting mechanism 25 for displacing the second shaft 12 in the radial direction, an example of rotating the second shaft 12 around the eccentric shaft 26 is illustrated, but the second shaft 12 is moved in the radial direction by other methods. You may employ | adopt what is displaced, for example, what slides the 2nd shaft 12 to radial direction.

The adjustment mechanism 25 is not necessarily provided.
The drive mechanism 22 for displacing the first shaft 11 in the radial direction is exemplified by rotating the first shaft 11 around the eccentric shaft 23. However, the first shaft 11 is moved in the radial direction by other methods. You may employ | adopt what is displaced, for example, what slides the 1st shaft 11 to radial direction.

  -When providing the variable valve mechanism which makes the opening / closing characteristic of the exhaust valve 3 variable, you may apply this invention to the variable valve mechanism.

Schematic which shows the structure of the variable valve mechanism of this embodiment. Schematic which shows operation | movement of a variable valve mechanism. Schematic which shows operation | movement of a variable valve mechanism. 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, 3 ... Exhaust valve, 4 ... Intake cam shaft, 4a ... Intake cam, 4b ... Cam nose, 5 ... Exhaust cam shaft, 5a ... Exhaust cam, 6 ... Variable valve mechanism, 7 ... Rocker arm, 8 ... lash adjuster, 9 ... valve spring, 10 ... roller, 11 ... first shaft, 12 ... second shaft, 13 ... input link, 14 ... auxiliary link, 15 ... output link, 16 ... pin, 17 DESCRIPTION OF SYMBOLS ... Roller, 18 ... Cam side contact part, 19 ... Pin, 20 ... Profile surface, 21 ... Valve side contact part, 22 ... Drive mechanism, 23 ... Eccentric shaft, 24 ... Motor, 25 ... Adjustment mechanism, 26 ... Eccentric shaft, 27: Support section.

Claims (5)

In a variable valve mechanism that varies the opening and closing characteristics of an engine valve that opens and closes based on the rotation of a cam of an internal combustion engine,
An input link that swings around the first shaft by the pressing of the rotating cam;
An auxiliary link swingable around a second shaft located closer to the engine valve than the first shaft and parallel to the shaft;
A first pin extending in the same direction as the first shaft is connected to the input link so as to be rotatable around the pin, and a second pin extends in the same direction as the second shaft with respect to the auxiliary link. An output in which a profile surface is formed to be pressed in the valve opening direction of the engine valve when the input link swings based on the rotation of the cam. Link,
A drive mechanism for displacing the first shaft in a radial direction;
With
The profile surface of the output link has a valve side contact portion that is a contact portion with the engine valve side, and the contact portion of the input link with the cam through the displacement of the first shaft by the drive mechanism. The distance in the opening and closing direction of the engine valve between the cam side contact portion and the valve side contact portion changes according to the position of the cam side contact portion when a certain cam side contact portion is displaced. A variable valve mechanism characterized by being formed. The engine valve is an intake valve,
The drive mechanism displaces the first shaft so that the cam side contact portion of the input link is displaced forward and backward in the rotation direction of the cam.
The profile surface of the output link is configured such that the cam side contact portion and the valve side contact portion become closer to the rear side in the rotation direction of the cam through the displacement of the first shaft by the drive mechanism. The variable valve mechanism according to claim 1, wherein a distance between the intake valve in the opening / closing direction of the intake valve is shortened. 3. The drive mechanism according to claim 1, wherein the drive mechanism is configured to displace the first shaft in a radial direction by rotating the shaft around a center line parallel to the axis of the first shaft. Variable valve mechanism. In the variable valve mechanism according to any one of claims 1 to 3,
The second shaft is arranged in the radial direction so that the distance in the opening / closing direction of the engine valve between the cam side contact portion in the input link and the valve side contact portion in the profile surface of the output link is variable. A variable valve mechanism characterized by further comprising an adjusting mechanism for displacing the valve. The variable valve according to claim 4, wherein the adjustment mechanism is configured to displace the second shaft in a radial direction by rotating the shaft around a center line parallel to the axis of the second shaft. mechanism.

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