JP2007162706A - Variable valve gear for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the driving load of an actuator resulting from the spring reaction of a valve spring to be transmitted to a control cam via a rocker arm. <P>SOLUTION: This variable valve gear comprises a drive shaft 13 having a driving cam 15 on the outer periphery, and a rocking cam 17 for giving opening/closing operation to an intake valve 12 rockingly supported on the drive shaft via a valve lifter 16. The rotating force of the driving cam is transmitted to the rocking cam via a link arm 24, the rocker arm 23 and a link rod 25, and the rotation of the control cam 33 on the outer periphery of a control shaft 32 is controlled to vary valve lift with a change of a first turn supporting point P1 on the side of one end 23a of the rocker arm. A second turn supporting point P2 between the rocker arm and the driving cam and a third turn supporting point P3 between the rocker arm and the rocking cam are arranged on the side of the other end 23b of the rocker arm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that can vary, for example, a valve lift amount of an intake valve or an exhaust valve according to an engine operating state.

As this type of conventional variable valve operating device, there is one described in the following Patent Document 1 and the like filed earlier by the present applicant. The variable valve device is applied to the intake valve side, and on the outer periphery of the drive shaft 51 rotating in synchronization with the rotation of the crankshaft, there is a drive cam 52 in which the axis Y is eccentric from the axis X of the drive shaft 51. In addition, the rotational force of the drive cam 52 is transmitted through a multi-link transmission mechanism, and the cam surface 55 is in sliding contact with the upper surface of the valve lifter 54 at the upper end of the intake valve 53. A swing cam 56 that opens and closes 53 is provided.

  The transmission mechanism includes a rocker arm 58 disposed above the swing cam 56 and supported swingably on the control shaft 57, and an annular base end portion 59a fitted to the outer peripheral surface 52a of the drive cam 52. The other end 59b is rotatably connected to one end 58a of the rocker arm 58 via a pin 60, and the one end 61a is rotatably connected to the other end 58b of the rocker arm 58 via a pin 62. The other end portion 61 b is composed of a link rod 61 that is rotatably connected to the end portion of the swing cam 56 via a pin 63.

  Further, a control cam 64 is fixed to the outer peripheral surface of the control shaft 57 so that the shaft center P1 is decentered from the shaft center P of the control shaft 57 by a predetermined amount. The control cam 64 is rotatably fitted and held in a support hole 58c drilled at substantially the center of the rocker arm 58, and the rocking fulcrum of the rocker arm 58 is changed in accordance with the rotation position to thereby swing the rocking cam 56. By changing the rolling contact position of the cam surface 55 with respect to the upper surface of the valve lifter 54, the valve lift of the intake valve 53 is variably controlled.

  That is, when the engine operating state is, for example, a low rotation and low load range, the control shaft 57 is rotated clockwise, for example, in the figure by an actuator such as an electric motor (not shown), and the control cam 64 is rotated in the same direction. As a result, the rocking fulcrum position of the rocker arm 58 is moved from the illustrated position to the left side. As a result, the pivot points of the rocker arm 58, the link arm 59, and the link rod 61 move to the left side to raise the end of the swing cam 56 on the cam nose portion 56a side. The upper contact position moves to the base portion 55a side. Therefore, the intake valve 53 is controlled so that its valve lift characteristic is a small lift.

  On the other hand, when shifting to the high rotation / high load range, the actuator controls the rotation of the control cam 64 to the illustrated position via the control shaft 57, so that the rocking fulcrum of the rocker arm 58 moves in the reverse direction. As a result, the end portion 56a of the swing cam 56 is pushed down by the link rod 61 or the like, and the contact position with the upper surface of the valve lifter 54 moves toward the lift top surface 55d, so that the valve lift of the intake valve 53 is large. It is controlled to be a lift.

Therefore, the engine performance such as improvement of fuel consumption and output can be sufficiently exhibited according to the engine operating state.
JP-A-11-107725

  However, in the conventional variable valve operating device, the valve lift characteristic can be made variable by changing the swing fulcrum of the rocker arm 58 in accordance with the rotational position of the control cam 64. No consideration is given to the load acting on the control shaft 57 during the rotation control of 64, that is, during the rotation of the control shaft 57.

That is, during the opening operation of the intake valve 53, acts as Fs to the swing cam 56 the spring force of the valve spring 53a via a valve lifter 54, whereby is applied the arrow direction of the moment M ₁ in FIG. 12. Due to this M _1, a reaction force f _{1 in the} direction connecting the shaft centers of both pins 62 and 63 of both ends 61 a and 61 b of the link rod acts on the link rod 61 via the pin 63, and the other end of the rocker arm 58. The reaction force f ₁ acts on the pin 58b via the pin 62. The rocker arm 58 receives a counterclockwise moment about the swing fulcrum by the reaction force f ₁ , but the reaction force f ₂ acts on one end 58 a of the rocker arm 58 via the pin 60, and this moment Will be balanced.

For this reason, the resultant force of the reaction forces f ₁ and f ₂ acting on the pin 62 and the pin 60 acts on the control cam 64 and a large load F is applied to the center P 1 of the control cam 64. For this reason, the product of the load F and the vector of the load F and the length t of the perpendicular dropped at the center P of the control shaft 57 acts on the control shaft 57 as a moment Mc.

  As a result, the drive load of the actuator that rotates the control shaft 57 increases, and a large loss of rotational drive energy occurs. Therefore, the size of the actuator is inevitably increased, and there is a possibility that power consumption due to driving of the actuator and fuel consumption of the engine are deteriorated.

  The present invention was devised in view of the actual situation of the variable valve system according to the prior application. The invention according to claim 1 rotates in synchronization with the crankshaft of the engine, and a drive cam is provided on the outer periphery. A drive shaft, a swing cam that opens and closes the engine valve in response to the swing, a rocker arm whose one end is swingably provided on the eccentric control cam via the first rotation fulcrum, and one end Is linked to the drive cam rotatably, the other end is linked to the rocker arm via a second pivot, and the other end of the rocker arm is linked to the rocker arm via a third pivot. A link rod linked to the end portion and linked to the swing cam at the other end portion, and a control shaft for controlling the rotation of the eccentricity control cam by an actuator, the rotational driving force of the drive cam being controlled by the link Swing via arm, rocker arm and link rod It is converted into motion and transmitted to the swing cam, and the swing fulcrum of the rocker arm is changed by controlling the rotational position of the eccentric control cam, and the valve lift amount of the engine valve by the swing cam is made variable. A variable valve operating apparatus for an internal combustion engine, wherein the second rotation fulcrum and the third rotation fulcrum are arranged on the other end side of the rocker arm, respectively, and when the maximum lift area of the engine valve is opened. As the drive cam rotates, the other end of the rocker arm is pulled down by the link arm via the second pivot fulcrum, whereby the link rod pushes down the swing cam, thereby lowering the engine valve. It is characterized by being configured to open.

  The invention according to claim 2 is characterized in that the second rotation fulcrum is disposed between the first rotation fulcrum and the third rotation fulcrum.

  The invention according to claim 3 is characterized in that the second pivot point and the third pivot point are disposed adjacent to each other end of the rocker arm via a coaxial pin.

  According to a fourth aspect of the present invention, the other end portion of the rocker arm is formed in a bifurcated shape, a second rotation fulcrum with which the drive cam is linked is disposed between the bifurcated portions, A third rotation fulcrum with which the pair of swing cams are linked to each other is arranged on both outer sides.

  According to a fifth aspect of the present invention, there is provided a second rotation fulcrum through which a coaxial pin passes through the bifurcated portion of the rocker arm and the drive cam is linked to the coaxial pin, and a pair of left and right swing cams. 3 rotation fulcrums are arranged.

  The invention according to claim 6 is characterized in that the side end of the base circle of the swing cam is linked to the other end of the link rod whose one end is linked via the third rotation fulcrum. Yes.

  As is apparent from the above description, according to the first aspect of the present invention, when the engine valve is opened, the third force due to the reaction force acting on the second pivot point from the drive cam and the spring force of the valve spring. The reaction force acting on the rotation fulcrum is canceled, and the load acting on the first rotation fulcrum is sufficiently reduced. For this reason, the drive load of the actuator is reduced, and the actuator can be miniaturized.

  As a result, the power consumption of the actuator can be reduced, and the deterioration of the fuel consumption of the engine can be prevented.

  According to the third aspect of the present invention, since the tilting moment of the rocker arm can be reduced, a phenomenon such as a shoulder contact of the rocker arm with respect to the control cam is prevented, and good rotation of the control cam can be obtained at all times. In this respect as well, the driving load of the actuator can be reduced.

According to the invention described in claim 4, since the tilting moment of the rocker arm can be further effectively reduced, the control cam can be further rotated. According to the invention described in claim 5, In the invention described in claim 4, the structure can be simplified and the number of parts can be reduced, so that the manufacturing work efficiency can be improved and the cost can be reduced.

  According to the sixth aspect of the present invention, it is possible to further prevent the component parts from projecting to the outside, thereby improving the layout.

  Hereinafter, embodiments of the variable valve operating apparatus of the present invention will be described in detail with reference to the drawings. The variable valve operating apparatus according to this embodiment includes two intake valves per cylinder and a variable mechanism that varies the valve lift amount of the intake valves in accordance with the engine operating state.

  That is, the variable valve operating apparatus includes a pair of intake valves 12 and 12 slidably provided on a cylinder head 11 via a valve guide (not shown) as shown in FIGS. A hollow drive shaft 13 that is rotatably supported by the bearing 14, a single drive cam 15 that is an eccentric rotary cam fixed to the drive shaft 13 by a connecting pin 40, and an outer peripheral surface of the drive shaft 13. Oscillating cams 17 and 17 that are supported in a swingable manner and are slidably contacted with valve lifters 16 and 16 disposed at upper ends of the intake valves 12 and 12 to open the intake valves 12 and 12, and drive The transmission mechanism 18 is linked between the cam 15 and the swing cams 17 and 17 and transmits the rotational force of the drive cam 15 as the swing force of the swing cams 17 and 17, and the operating position of the transmission mechanism 18 is variable. The variable mechanism 19 is provided.

  The drive shaft 13 is arranged along the longitudinal direction of the engine and is rotated from the crankshaft of the engine via a driven sprocket (not shown) provided at one end, a timing chain wound around the driven sprocket, and the like. The force is transmitted, and the rotation direction is set in the counterclockwise direction in FIG. The drive shaft 13 is made of a high strength material.

  The bearing 14 is provided at the upper end portion of the cylinder head 11 to support the upper portion of the drive shaft 13, and the bearing 14 is provided at the upper end portion of the main bracket 14a to rotatably support a control shaft 32 described later. The brackets 14a and 14b are fastened together from above by a pair of bolts 14c and 14c.

  The drive cam 15 is integrally formed of a wear-resistant material and has a substantially ring shape as shown in FIG. 2, and an annular cam body 15a and a cylinder integrally provided on the outer end surface of the cam body 15a. The drive shaft insertion hole 15c is formed through the inner shaft direction, and the shaft center Y of the cam body 15a is offset from the shaft center X of the drive shaft 13 in the radial direction by a predetermined amount. . The drive cam 15 is connected and fixed to the drive shaft 13 by a connecting pin inserted through the drive shaft 13 from the radial direction of the cylindrical portion 15b, and on one side surface of the cylindrical portion 15b on the cam body 15a side. A crescent-shaped flat part is formed. Further, the drive cam 15 rotates in the counterclockwise direction in FIG. 2 as the drive shaft 13 rotates as shown in FIG.

  The valve lifters 16 and 16 are formed in a cylindrical shape with a lid, are slidably held in the holding holes of the cylinder head 11, and upper surfaces 16 a and 16 a to which the swing cams 17 and 17 are slidably contacted are flat. Is formed.

  As shown in FIGS. 1 and 2, the rocking cams 17, 17 have a substantially raindrop shape, and a support hole 20 a that is rotatably supported on the outer peripheral surface of the drive shaft 13 is formed in a substantially cylindrical base end portion 20. In addition to being formed through, a pin hole 21a is formed through the cam nose 21 at one end. A cam surface 22 is formed on the lower surface of the swing cam 17, and the cam surface 22 has a base circle surface 22 a on the base end portion 20 side and a circular shape from the base circle surface 22 a to the cam nose portion 21 side. A ramp surface 22b extending in an arc shape and a lift surface 22c connected to the top surface 22d of the maximum lift from the ramp surface 22b on the tip side of the cam nose portion 21 are formed. The base circle surface 22a, the ramp surface 22b, The surface 22c and the top surface 22d come into contact with predetermined positions on the upper surface 16a of each valve lifter 16 according to the swing position of the swing cam 17.

  That is, a predetermined angle range of the base circle surface 22a becomes a base circle interval, a predetermined angle range from the base circle interval of the ramp surface 22b becomes a so-called ramp interval, and a predetermined angle from the ramp interval of the ramp surface 22b to the top surface 22c. The range is set to be the lift section.

  The transmission mechanism 18 is disposed above the drive shaft 13 and has a rocker arm 23 having a cylindrical end portion 23a supported so as to be swingable, and a link that links the other end portion 23b of the rocker arm 23 and the drive cam 15. An arm 24 and a link rod 25 for linking the rocking cam 17 with a different part of the other end 23 b of the rocker arm 23 are provided.

  As shown in FIG. 1, the rocker arm 23 is supported at one end 23a by a control cam 33, which will be described later, via a support hole 23c so as to be swingable, and the shaft center P1 of the control cam 33 is first rotated. It is a fulcrum. Further, the other end portion 23b protruding from the outer end portion of the one end portion 23a is formed in a bifurcated shape, and a projection of a link arm 24 described later on the outer side portion of the relatively thick one portion 23c of the bifurcated portion. A pin 26 for rotatably connecting the end 24b is projected, and a pin 27 for rotatably connecting one end portion 25a of the link rod 25 is interposed between the one portion 23c and the other portion 23d. Yes.

  The link arm 24 includes a base end portion 24a which is a relatively large-diameter annular one end portion, and a projecting end 24b which is the other end portion projecting at a predetermined position on the outer peripheral surface of the base end portion 24a. A pin hole through which the pin 26 is rotatably inserted is formed in the protruding end 24b. The axis P2 of the pin 26 serves as a second rotation fulcrum that rotatably supports the other end 23b of the rocker arm 23.

  Further, as shown in FIG. 1, the link rod 25 is formed in a substantially square shape having a concave shape on the rocker arm 23 side. A pin insertion hole through which the end portion of each pin 27, 28 press-fitted into each pin hole of the cam nose portion 21 is rotatably inserted is formed. The axis P3 of the pin 27 is a third rotation fulcrum, and the axis P3 and the axis P2 of the pin 26 that is the second rotation fulcrum are slightly in the vertical direction and the front-rear direction. Is offset.

  A snap ring (not shown) that restricts the axial movement of the link arm 24 and the link rod 25 is provided at one end of each pin 26, 27, 28.

  The variable mechanism 19 includes a control shaft 32 that is rotatably supported by the same bearing 14 above the drive shaft 13, and a control cam 33 that is fixed to the outer periphery of the control shaft 32 and serves as a swing fulcrum of the rocker arm 23. It has.

  As shown in FIG. 1, the control shaft 32 is disposed in the longitudinal direction of the engine in parallel with the drive shaft 13, and is rotated at a predetermined rotation angle by an electric motor 29 that can rotate forward and backward as an actuator provided at one end. It is designed to rotate within the range.

  Further, the control cam 33 has a cylindrical shape, and the position of the shaft center P1 is deviated from the shaft center P of the control shaft 32 by α as shown in FIG.

  Further, the electric motor 29 that controls the rotation of the control shaft 32 is driven by a control signal from a controller 30 that detects the operating state of the engine. The controller 30 detects the current engine operating state by calculation based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a water temperature sensor, and detects a rotational position of the control shaft 32. A control signal is output to the electric motor 29 based on a detection signal from 31.

  Hereinafter, the operation of the present embodiment will be described. First, at the time of engine low speed and low load, the control shaft 32 is rotationally driven to the position shown in FIG. 2 via the electric motor 29 by the control signal from the controller 30. Therefore, the control cam 33 is held at the rotation angle position in the left direction from the axis P of the control shaft 32 as shown in FIG. 2, and the thick portion 33a is moved in the left direction from the drive shaft 13. To do. For this reason, the entire rocker arm 23 moves to the left and rotates counterclockwise around P2. For this reason, P3 moves to the upper left, and each rocking cam 17 is forcibly pulled up slightly by the cam nose part 21 side via the link rod 25, and the whole is rotated to the illustrated position.

  Therefore, when the drive cam 15 rotates as shown in FIG. 2 and the other end 23 b of the rocker arm 23 is pulled up via the link arm 24, the lift amount of the rocker cam 17 and the valve lifter 16 is increased via the link rod 25. However, the lift amount L1 becomes small as shown in FIG.

  Therefore, in such a low-speed and low-load region, the valve lift amount is reduced as shown in FIG. 5, friction is reduced, the opening timing of each intake valve 12 is delayed, and the valve overlap with the exhaust valve is reduced. For this reason, improvement in fuel consumption and stable rotation of the engine can be obtained.

  On the other hand, when the engine speed is changed to a high load, the control shaft 32 is driven to rotate clockwise by the electric motor 29 in accordance with a control signal from the controller. Therefore, as shown in FIGS. 3 and 4, the control shaft 32 rotates the control cam 33 clockwise from the position shown in FIG. 2, and moves the axis P1 (thick portion 33a) to the upper right. For this reason, the rocker arm 23 is now moved to the right as a whole, and is rotated clockwise around P2, whereby P3 is moved to the lower right, and the other end 23b is the cam nose of the swing cam 17. The portion 21 is pressed downward via the link rod 25 to rotate the entire swing cam 17 clockwise by a predetermined amount. 3 shows an open operation state (the moment when the maximum lift is reached), and FIG. 4 shows a closed state.

  Therefore, the contact position of the cam surface 22 with respect to the upper surface 16a of the valve lifter 16 of the swing cam 17 is moved to the right position (the lift portion 22c side) with respect to the position shown in FIG. Therefore, when the drive cam 15 rotates as shown in FIG. 3 and the other end 23b of the rocker arm 23 is pulled down via the link arm 24, the lift amount L2 with respect to the valve lifter 16 increases as shown in FIG. .

  Therefore, in such a high speed and high load region, the cam lift characteristic is larger than that in the low speed and low load region, the valve lift amount is increased as shown in FIG. 5, the opening timing of each intake valve 12 is advanced, and the closing time is closed. The time is late. As a result, the intake charging efficiency is improved and a sufficient output can be secured.

  And according to this embodiment, both the said 2nd rotation fulcrum P2 and the 3rd rotation fulcrum P3 with respect to the 1st rotation fulcrum P1 by the side of the one end part 23a of the rocker arm 23 are used for the rocker arm 23. Since they are arranged side by side on the other end 23b side, as described above, the load F acting on the axis P1 of the control cam 33 particularly during rotation from the minimum lift position to the maximum lift control is compared with that of the previous application. Small enough.

That is, for example, as shown in FIG. 3, when the intake valves 12 and 12 are opened in the maximum lift range, the spring force of the valve spring 12a acts as Fs on the swing cam 17 via the valve lifter 16, As a result, a counterclockwise moment M ₁ is applied. Due to this M _1, the reaction force f _{1 in the} direction connecting the shafts 27 and 28 of both ends 25 a and 25 b of the link rod 25 acts on the link rod 25 via the pin 28, and the other end of the rocker arm 23. the 23b, although the reaction force f ₁ is applied through the pin 27, since also the second pivot point P2 is located on the third pivot point P3 side, as shown in FIG. 3, The direction of the reaction force f ₂ is opposite to that of the previous application. For this reason, both reaction forces f ₁ and f ₂ are canceled out.

The reason why the direction of the reaction force f ₂ is opposite to that of the prior application is that when the intake valves 12, 12 are pushed down via the swing cam 17, the drive cam 15 side (link arm 24) ) Is performed by pushing up the rocker arm 23, the reaction force f ₂ is directed in the direction opposite to the drive shaft 13 (upward), whereas in this embodiment, the reaction force is as described above. The second rotation fulcrum P2 on which f ₂ acts is on the side of the third rotation fulcrum P3 on which the reaction force f ₁ acts against the first rotation fulcrum that is the axis P1 of the control cam 33. This is because the above-described depression of the intake valve 12 is performed by pulling down the rocker arm 23 via the link arm 24 via P2.

The force of the load F acting on the first rotation fulcrum P1 of the rocker arm 23 is sufficiently reduced by canceling out the reaction forces f ₁ and f ₂ . As a result, the moment Mc acting around the control shaft 32 is also sufficiently reduced, and the driving load applied to the electric motor 29 can be significantly reduced.

  Note that when the intake valves 12 and 12 are closed as shown in FIG. 4, since a large spring reaction force from the valve spring 12a is not generated, the load F is also small, so that the generation of a load on the electric motor 29 is not a problem. .

  6 and 7 show a second embodiment in which the protruding end 24b of the link arm 24 connected to the other end 23b of the rocker arm 23 and the one end 25a of the link rod 25 are connected by the same pin 40. FIG. Thus, the second rotation fulcrum P2 and the third rotation fulcrum P3 are arranged on the same axis. FIG. 6 shows the open operation state (the moment when it stops at the maximum lift), and FIG. 7 shows the closed state.

Therefore, in this embodiment, in the open operation state in the maximum lift control of the intake valves 12 and 12 shown in FIG. 6, the second and third rotation fulcrums P2 and P3 are the other ends of the rocker arm as in the first embodiment. Since it is arranged on the side of the part 23b, the value of F becomes small due to the canceling action of the two reaction forces f ₁ and f ₂ , and since it is arranged on the same axis, For example, the clearance between the link arm 24 and the control shaft 32 increases, and the area formed by both the swing trajectory of the link arm 24 and the swing trajectory of the link rod 25 can be reduced. Improvement and downsizing of the device can be achieved.

  In addition, since both 24 and 25 are supported by the same pin 40, the structure is simplified, the number of parts can be reduced, the manufacturing work is facilitated, and the cost can be reduced.

  FIGS. 8 and 9 show the third embodiment, in which the protruding end 24b of the link arm 24 and the one end 25a of the link rod 25 are arranged in parallel on one side, not on both sides of the rocker arm other end 23a. Then, both the pins 24b and 25a are rotatably connected to the rocker arm other end portion 23b by a single pin 41. Therefore, the second rotation fulcrum P2 and the third rotation fulcrum P3 are disposed adjacent to each other. The other end portion 25b of the link rod 25 is rotatably connected to the upper end portion on the base circle surface 22a side, not the cam nose portion 21 side of one swing cam 17 via a pin 28, so that the link rod When 25 is pushed up, the cam nose portion 21 of the swing cam 17 is pushed down to open the intake valve 12.

In this way, if the base circle surface 22a is connected, f ₁ generated against F _S is in the downward direction opposite to the first and second embodiments, and f ₂ is also the first, Although it is the reverse of the second embodiment, f ₁ and f ₂ are the same in the reverse direction, and the effect of reducing F is obtained in the same way. In this embodiment, since the link rod 25 does not protrude outward, there is a merit in layout.

  Furthermore, according to this embodiment, by arranging the both 24b and 25a in parallel on one side of the rocker arm other end 23b, a so-called twisting phenomenon during operation can be avoided.

That is, if it is assumed that the other end 24b of the link arm 24 and the one end 25a of the link rod 25 are respectively arranged on both sides of the other end 23b of the rocker arm 23, the swing cam 17 side reaction force f ₁ moment Mt1 prying due to the reaction force f ₂ of prying moments Mt2 the drive cam 15 side with respect to the rocker arm and the other end portion 23b by the turned in the same direction, the large twisting moment Mt to the one end portion 23a of the rocker arm 23 (= Mt1 + Mt2 ) May occur. As a result, the shoulder contact with the outer peripheral surface of the control cam 33 by the inner peripheral surface of the support hole 23d occurs, and the frictional resistance increases, and the pivotability of the control cam 33 may deteriorate.

  However, by arranging both 24b and 25a on one side of the other end 23b as in the present embodiment, the twisting moments Mt1 and Mt2 act in opposite directions. For this reason, the two twisting moments Mt1 and Mt2 are offset, and the twisting moment Mt with respect to the one end portion 23a of the rocker arm 23 is sufficiently reduced. Rotation is obtained.

  FIG. 10 shows a fourth embodiment, in which the swing cams 17 and 17 are separated from each other and brought into contact with the intake valves 12 and 12 respectively, and the corresponding link rods 25 and 25 are also paired. On the other hand, the other end portion 23b of the rocker arm 23 is formed in a bifurcated shape, and the protruding end 24b of the link arm 24 on the drive cam 15 side is interposed in the central gap portion 23d, and both outer side portions of the other end portion 23b. The one end portions 25a and 25a of the link rods 25 and 25 are arranged on the same axis, and the protruding end 24b and both link rod one end portions 25a and 25a are coaxially connected by a single pin 42 penetrating the other end portion 23b. Concatenated. Accordingly, the second rotation fulcrum P2 and the two third rotation fulcrums P3 and P3 are juxtaposed on the other end 23b side.

  The other end portions 25b and 25b of the link rods 25 and 25 are also formed in a bifurcated shape, and the upper ends of the swing cams 17 and 17 are sandwiched between the bifurcated portions of the other end portions 25b and 25b. Thus, the rocking cams 17 and 17 are rotatably supported by the pins 28 and 28 penetrating the other end portions 25b and 25b.

  Thus, by arranging the second rotation fulcrum P2 between the third rotation fulcrums P3 and P3, the twisting moments Mt2 and Mt2 at the third rotation fulcrums P3 and P3 are opposite to each other. Therefore, the twisting moment Mt (falling moment) with respect to the rocker arm 23 is significantly reduced. As a result, the twisting moment acting on the control cam 33 becomes extremely small, and a better rotation of the control cam 33 can be obtained.

  Furthermore, as described above, since it is constituted by one pin 42, the structure can be simplified and the number of parts can be reduced, so that the manufacturing work efficiency can be improved and the cost can be reduced.

  Further, since the end portions of the swing cams 17 and 17 are supported in a supported state so as to be sandwiched between the bifurcated other end portions 25b and 25b of the link rods 25 and 25, the swing cams 17 and 17 17 can be prevented from falling down, and the rocking cams 17 and 17 can be always supported in a good rotation.

The principal part perspective view which shows the 1st embodiment of this invention. Action explanatory drawing which shows the open operation state at the time of the minimum lift control of this embodiment seen from the arrow A direction of FIG. Action | operation explanatory drawing which shows the open operation state at the time of the maximum lift control of this embodiment. Explanatory drawing which shows the same closed state. The valve lift characteristic view of this embodiment. Explanatory drawing at the time of the opening action of 2nd Embodiment. Explanatory drawing at the time of the closing operation. The principal part sectional view of a 3rd embodiment. BB sectional drawing of FIG. Sectional drawing of the principal part of 4th Embodiment. Sectional drawing which shows the conventional variable valve apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Intake valve 13 ... Drive shaft 15 ... Drive cam 17 ... Swing cam 22 ... Cam surface 23 ... Rocker arm 24 ... Link arm 24a ... Cylindrical base 24b ... Projection end 25 ... Link rod 26 ... Pin 27 ... Pin 32 ... Control Shaft 33 ... Control cam P1 ... First rotation fulcrum P2 ... Second rotation fulcrum P3 ... Third rotation fulcrum

Claims (6)

A drive shaft that rotates in synchronization with the crankshaft of the engine and has a drive cam provided on the outer periphery;
A swing cam that opens and closes the engine valve in accordance with the swing;
A rocker arm having one end swingably provided on the eccentric control cam via the first rotation fulcrum;
A link arm having one end portion rotatably connected to the drive cam and the other end portion linked to the rocker arm via a second rotation fulcrum;
A link rod having one end linked to the other end of the rocker arm via a third pivot, and the other end linked to the swing cam;
A control shaft that controls rotation of the eccentric control cam by an actuator, and
The rotational driving force of the drive cam is converted into a swing motion via the link arm, rocker arm and link rod and transmitted to the swing cam, and the rocker arm swing is controlled by the rotational position control of the eccentric control cam. A variable valve operating device for an internal combustion engine that varies a dynamic fulcrum to vary a valve lift amount of the engine valve by the swing cam,
The second rotation fulcrum and the third rotation fulcrum are arranged on the other end side of the rocker arm, respectively.
During opening operation of the maximum lift range of the engine valve, the other end portion of the rocker arm is pulled down by the link arm through the second rotation fulcrum with the rotation of the drive cam. A variable valve operating device for an internal combustion engine, wherein the engine valve is opened by pushing down a swing cam. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the second rotation fulcrum is disposed between the first rotation fulcrum and the third rotation fulcrum. The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein a second rotation fulcrum and a third rotation fulcrum are disposed adjacent to each other end of the rocker arm via a coaxial pin. The other end portion of the rocker arm is formed in a bifurcated shape, a second rotation fulcrum with which the drive cam is linked is disposed between the bifurcated portions, and a pair of the swinging motions on both outer sides of the bifurcated portion. The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2, wherein a third rotation fulcrum with which each cam is linked is arranged. A bifurcated portion of the rocker arm is provided with a second rotation fulcrum that penetrates the coaxial pin and the drive cam is linked to the coaxial pin, and a third rotation fulcrum of the pair of left and right swing cams. The variable valve operating apparatus for an internal combustion engine according to claim 4, wherein: 6. The side end of the base circle of the rocking cam is linked to the other end of the link rod whose one end is linked via the third rotation fulcrum. The variable valve operating apparatus for an internal combustion engine according to one item.

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