JP2004360467A - Valve train for internal combustion engine - Google Patents

Abstract

An object of the present invention is to prevent free tilting of a link arm, prevent local wear with a driving cam, and improve durability.
A rotational force of a drive cam is transmitted to two swing cams via a link arm, a rocker arm, and a link rod to open and close each intake valve and to control a control shaft. The rotation of the cam 17 variably controls the valve lift of the intake valve. The two oscillating cams are arranged on both sides of the link arm, and the ring arms of the link arm are provided via both bearings 24, 24 by extending portions 27a to 28b integrally formed between the opposing end surfaces of the two oscillating cams. The portion 11a is supported in a sandwiched state from both sides in the axial direction of the drive shaft, and inadvertent movement in the axial direction is restricted to prevent free tilting of the link arm.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a valve operating device for an internal combustion engine, in particular, an internal combustion engine having two oscillating cams for driving two intake valves per cylinder, and using the two oscillating cams to prevent an inadvertent tilt of the link arm. The present invention relates to a valve train for an engine.
[0002]
[Prior art]
As this kind of conventional valve train, there is one described in the following patent document, which was previously filed by the present applicant.
[0003]
In brief, this valve operating device is applied to a device having two intake valves per cylinder, and has a shaft centered on the outer periphery of a drive shaft that rotates synchronously with the rotation of a crankshaft. A drive cam eccentric from the center is fixedly provided, and two cylindrical camshafts are rotatably provided coaxially on the outer periphery of the drive shaft.
[0004]
Each of the camshafts is provided integrally with a pair of left and right swinging cams corresponding to a pair of intake valves on the outer periphery thereof, and the rotational force of the driving cam is transmitted to the two swinging cams in a multi-node link shape. The air is transmitted through a mechanism, and each intake valve is opened and closed via a valve lifter.
[0005]
The transmission mechanism is disposed above each swing cam, and a rocker arm that is swingably supported on the control shaft via the control cam, an annular portion at one end is rotatably linked to the drive cam, and A link arm whose other end in the form of a protrusion is rotatably connected via a pin between one ends of a so-called two-sided width of the rocker arm, and one end in which the other end of the rocker arm has a bifurcated shape via a pin. It is rotatably connected, and is constituted by a pair of link rods whose other end is rotatably connected to the cam nose portion side of each swing cam via a pin.
[0006]
The rocking cams are provided at symmetrical positions on both the left and right sides of the drive cam (link arm). The rocking arms can be simultaneously rocked by the other forked ends of the rocker arm. Thus, the occurrence of variations in the opening and closing lift of both intake valves is prevented.
[0007]
[Patent Document 1]
JP-A-2002-38913
[Problems to be solved by the invention]
By the way, in the conventional valve operating device, a multi-joint link mechanism including a link arm, a rocker arm, and a link rod is used as means for transmitting the rotational force of the driving cam to each swing cam. In addition, each component of each multi-link mechanism operates violently with the operation of the engine. Therefore, high dimensional accuracy and high positioning accuracy of each component are required in order to suppress occurrence of wear and operation noise of each component.
[0009]
However, particularly in the link arm of the above-described multi-link mechanism, the projection on the other end is disposed between the two flat ends of the rocker arm so that the movement in the axial direction is restricted, and the positioning accuracy is relatively high. However, since the annular portion on the other end side that slidably holds the drive cam inside does not have any movement restricting means in the axial direction of the drive shaft, it moves slightly in the axial direction. Therefore, the link arm may slightly tilt left and right toward the axial side of the drive shaft, and the link arm may flutter.
[0010]
For this reason, in particular, a part of the inner peripheral surface of the annular portion and a part of the outer peripheral surface of the drive cam are generated, so that abrasion easily occurs locally, resulting in a decrease in durability.
[0011]
[Means for Solving the Problems]
The present invention has been devised in view of the actual situation of the conventional valve gear, and the invention according to claim 1 has both oscillating cams disposed on both sides of a driving cam and the two oscillating cams. The annular portion of the link arm is supported between opposite end surfaces of the drive arm so as to be sandwiched from both sides in the axial direction of the drive shaft.
[0012]
Therefore, according to the present invention, both sides of the ring portion of the link arm are supported, for example, in contact with each other in a state of being sandwiched between the opposing end surfaces of the two swing cams, that is, in a state where the operation of the link arm and each swing cam is not hindered. Thereby, the free movement in the axial direction on the annular portion side is restricted. For this reason, the tilting of the link arm is prevented, and a partial contact between the inner peripheral surface of the annular portion and the outer peripheral surface of the drive cam is prevented. As a result, the occurrence of wear is prevented, and the durability can be improved.
[0013]
The invention according to claim 2 is characterized in that a shim is provided between at least one of the opposite end faces of the two swing cams and the link arm.
[0014]
According to the present invention, since the end face of the swing cam that swings separately and the link arm do not directly slide, the occurrence of wear is prevented. Furthermore, even if the width of the swing cam, that is, the axial length of the drive shaft varies due to the provision of the shim, and the accurate positioning of the swing cam cannot be performed, the gap can be adjusted by the shim. Thus, free movement of the annular portion of the link arm in the axial direction can be reliably restricted.
[0015]
The invention according to claim 3 is characterized in that a lubricating oil supply circuit for supplying lubricating oil from the inside of the drive shaft to between the drive cam and the annular portion is provided.
[0016]
According to this invention, the lubricating oil is forcibly supplied between the outer peripheral surface of the drive cam and the inner peripheral surface of the annular portion, and the lubricating performance between the two is improved. Therefore, in combination with the free movement restriction action of the annular portion in the axial direction, it is possible to effectively prevent the wear between the annular portion and the drive cam.
[0017]
In addition, since the lubricating oil flowing out from between the inner peripheral surface of the annular portion and the outer peripheral surface of the drive cam is also supplied between the annular portion and each of the swing cams, the lubrication performance of such a portion is also reduced. improves.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a valve train for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. The valve gear of this embodiment is applied to an internal combustion engine provided with two intake valves per cylinder and a variable mechanism for varying the valve lift of each intake valve in accordance with the engine operating state, as in the prior art. I have.
[0019]
1 to 5 show a valve train according to a first embodiment. A pair of intake valves 2 and 2 slidably provided on a cylinder head 1 via a valve guide (not shown) and an engine An internally hollow drive shaft 3 arranged in the front-rear direction, a drive cam 4 fixed to a predetermined position of the drive shaft 3, and a drive cam 4 centered on the drive shaft 3 while being swingably supported by the drive shaft 3. A pair of oscillating cams 5 and 5 which are arranged at symmetric positions and open the respective intake valves 2 and 2 via valve lifters 6 and 6, and between a driving cam 4 and oscillating cams 5 and 5. It is provided with a transmission mechanism 7 that is linked and transmits the rotational force of the driving cam 4 as the oscillating power (valve opening force) of the oscillating cams 5, and a control mechanism 8 that makes the operating position of the transmission mechanism 7 variable. ing.
[0020]
The intake valves 2, 2 are moved in the closing direction by valve springs 9, 9 elastically mounted between the bottom of a substantially cylindrical bore housed in the upper end of the cylinder head 1 and a spring retainer at the upper end of the valve stem. Being energized.
[0021]
The drive shaft 3 is disposed along the engine front-rear direction, and both ends are rotatably supported by a plurality of bearings 24 provided on an upper portion of the cylinder head 1 and are provided at one end. Rotational force is transmitted from the crankshaft of the engine via an external driven sprocket or a timing chain wound around the driven sprocket, and the rotation direction is set clockwise in FIG. As shown in FIG. 1, each of the bearings 24 is disposed outside the intake valves 2 and 2, and is formed integrally with an upper end of the cylinder head 1 and has a base 24 a having a semicircular bearing groove in the center. And a bracket 24b having a semicircular bearing groove for supporting the drive shaft 3 together with the bearing groove at the center thereof, which is disposed above the base 24a. Each bracket 24b is fixed to the base 24a by two bolts 25 and 26, respectively.
[0022]
The drive cam 4 is formed in a substantially disk shape and is formed integrally with the drive shaft 3, and the center Y is provided at a position eccentric from the axis X of the drive shaft 3, and the outer peripheral surface 4 a is eccentric. It is formed in a circular cam profile.
[0023]
As shown in FIG. 2, each of the swing cams 5 has substantially the same shape as a raindrop, and the base end 5 a swings about the axis X of the drive shaft 3 via the camshaft 4. The cam surface 5b is formed on the lower surface, and the cam surface 5b is formed with a base circular surface on the base end portion 5a side and a ramp extending from the base circular surface to the cam nose portions 5c and 5c in an arc shape. Surface and a lift surface that is continuous from the ramp surface to the top surface of the largest lift provided on the tip end side of the cam nose portion 5c. The base circular surface and the ramp surface, the lift surface, and the top surface 5 is brought into contact with a predetermined position on the upper surface of each valve lifter 6 according to the swing position.
[0024]
In each of the swing cams 5, 5, the base end portion 5a is formed so as to be vertically divided in a half-shape with respect to the drive shaft 3, and the divided portions 5d, 5e are vertically divided by front and rear bolts 23, 23. The semi-circular inner surfaces are formed on a cylindrical sliding surface 5f that is in sliding contact with the outer peripheral surface of the drive shaft 3 in the coupled state.
[0025]
The transmission mechanism 7 includes a rocker arm 10 disposed above the drive shaft 3, a link arm 11 for linking one end 10 a of the rocker arm 10 and the drive cam 4, and a rocking arm 10. And a pair of link rods 12 that link the cam 5 with the link rods 12.
[0026]
The rocker arm 10 has a support hole 10c formed in the center of the cylindrical base portion from the lateral direction, and is swingably supported by a control cam 17 to be described later via the support hole 10c. One end 10a extending from one side in the radial direction of the cylindrical base has a cutout 10d formed in the center to form a so-called two-plane width, while extending from the other side of the cylindrical base. The other end portions 10b and 10b, which are the arm portions, are formed in a forked shape corresponding to the two swing cams 5. The bifurcated other ends 10b and 10b are arranged at symmetric positions with respect to the cylindrical base, and a pin hole 10d into which a pin 20 connected to the one end 12a of the link rod 12 is fitted at each of the distal ends. 10d are formed through each. The other end portions 10b and 10b transmit the oscillating power to the two oscillating cams 5 from the upper side in the direction of gravity via the respective link rods 12 and 12. Further, in the rocker arm 10, the entire lower surface 10e on the drive cam 4 side is formed in a concave curved surface shape.
[0027]
The link arm 11 has a relatively large-diameter annular portion 11a at one end and a projecting end 11b at the other end protruding at a predetermined position on the outer peripheral surface of the annular portion 11a. At the center position, a fitting hole 11c into which the outer peripheral surface 4b of the driving cam 4 is rotatably fitted is formed, while the protruding end 11b is inserted into a notch 10d of one end 10a of the rocker arm 10. It is arranged and is rotatably connected to the one end 10a by a pin 13 inserted into a pin hole 11d penetratingly formed in the inner axial direction. The thickness of the annular portion 11a in the axial direction of the drive shaft 3 is set slightly larger than the thickness of the drive cam 4, and the drive cam 4 is held inside the annular portion 11a. It is supposed to.
[0028]
The link rod 12 is bent into a substantially U-shaped cross section by press molding, and has two plates near both ends 12a and 12b, through which pin holes 12c and 12d are formed. The pin holes 12c and 12d are rotatably connected to the pins 14 rotatably connected to the other ends 10b and 10b of the rocker arm 10 and the cam nose portions 5c and 5c of the swing cams 5 and 5 respectively. The pin 15 is inserted.
[0029]
The control mechanism 8 includes a control shaft 16 rotatably supported by a bearing (not shown) disposed above the cylinder head 1, and a swing fulcrum of the rocker arm 10 fixed to the outer periphery of the control shaft 16. And a control cam 17 which becomes
[0030]
The control shaft 16 is disposed in the engine front-rear direction in parallel with the drive shaft 3 and within a predetermined rotation angle range via a gear mechanism by an unillustrated electric actuator (DC motor) provided at one end. The rotation is controlled. On the other hand, the control cam 17 has a cylindrical shape, and the position of the axis P1 is deviated by a predetermined amount from the axis P2 of the control shaft 16 by the thickness.
[0031]
The electric actuator is driven by a control signal from a controller (not shown) that detects the operating state of the engine. This controller has a built-in microcomputer, a crank angle sensor, an air flow meter, and a water temperature sensor. Further, based on detection signals from various sensors such as a potentiometer for detecting the rotational position of the control shaft 16, the current engine operating state is detected by calculation or the like, and a control signal is output to the electric actuator.
[0032]
As shown in FIG. 1, each of the swing cams 5 and 5 has a cylindrical extension at an end face of each of the base ends 5a and 5a, that is, at a hole edge on both sides of each sliding face 5f. The parts 27a, 27b, 28a, 28b are respectively formed integrally. Each of the extending portions 27a, 27b, 28a, and 28b has an entire length in the axial direction including the base end portion 5a, which extends from the facing surface of each of the bearings 24, 24 to the annular portion 11a of the link arm 11. It is formed up to the vicinity of both sides in the axial direction, and supports the annular portion 11a by sandwiching the annular portion 11a from both sides by the opposed inner end surfaces of the opposed inner extension portions 27a and 28a. On the other hand, the outer end surfaces of the outer extension portions 27b, 28b are in contact with the opposing surfaces of the bearings 24, 24. Therefore, in the annular portion 11a, free movement in the axial direction is restricted by the extension portions 27a, 27b, 28a, 28b via the dual bearings 24, 24.
[0033]
Further, lubrication is performed between the outer peripheral surface of the drive cam 4 and the inner peripheral surface of the fitting hole 11c of the link arm 11, and between the outer peripheral surface of the control cam 17 and the inner peripheral surface of the support hole 10c of the rocker arm 10. A lubricating oil supply circuit is provided.
[0034]
That is, as shown in FIGS. 1 and 2, the lubricating oil supply circuit includes a first oil passage 18 formed along an inner axial direction of the drive shaft 3, a diametric direction of the drive shaft 3, and a drive cam. A first communication passage 19 formed continuously in the radial direction inside the first communication passage 4 and communicating between the first oil passage 18, the outer peripheral surface 4 a of the drive cam 4 and the fitting hole 11 c of the link arm 11. A second oil passage 20 formed along the direction of the internal axis of the control shaft 16, a diametric hole 21 formed in the diameter direction of the control shaft 16 and communicating with the second oil passage 20, The control cam 17 includes a second communication passage 22 formed radially in the thick portion of the control cam 17 and communicating between the diameter hole 21, the inner surface of the support hole 10 c of the rocker arm 10, and the outer surface of the control cam 17. Have been.
[0035]
The first oil passage 18 has an oil introduction passage 30 formed continuously from the oil gallery inside the cylinder head 1 to the inside of the bearing 24, and an oil hole 31 formed radially in the peripheral wall of the drive shaft 3. Lubricating oil is introduced to the inside through the lubricating oil. Further, lubricating oil is also introduced into the second oil passage 20 from the oil gallery through an oil introduction passage formed in a bearing (not shown) and a radial oil hole of the control shaft 16. I have.
[0036]
In the following, the operation of the variable mechanism according to the present embodiment will be briefly described. At the time of low-lift control, the control shaft 16 is driven to rotate in one direction via an electric actuator by a control signal from the controller. For this reason, as shown in FIGS. 7A and 7B, the control cam 17 has the thick portion rotated rightward in the drawing with respect to the control shaft 16 and is held at the rotation angle position. Thereby, the other end 10b side of the rocker arm 10 rotates upward. For this reason, each swing cam 5 is forcibly pulled up on the cam nose portion 5c side via the link rod 12, and the whole is held at the clockwise rotation position in FIG.
[0037]
Accordingly, when the drive cam 4 rotates and the link arm 11 pushes up one end 10a of the rocker arm 10, the lift amount is transmitted to the swing cam 5 and the valve lifter 6 via the link rod 12, as shown in FIG. 7B. However, the lift amount becomes sufficiently small.
[0038]
Therefore, the valve lift (L1) of the intake valves 2 and 2 is reduced, the opening timing is delayed, and the valve overlap with the exhaust valve is reduced. For this reason, for example, improvement in fuel efficiency in a low load region and stable rotation of the engine can be obtained.
[0039]
On the other hand, during the high-lift control, the control shaft 16 is rotationally driven in the other direction by the electric actuator according to the control signal from the controller. Therefore, as shown in FIGS. 8A and 8B, the control shaft 16 rotates the control cam 17 to a predetermined rotation angle position, and moves the thick portion downward. For this reason, the other end 10b side of the rocker arm 10 moves downward to push the cam nose portion 5c of the swing cam 5 downward via the link rod 12, and the whole swing cam 5 moves clockwise in FIG. It is held in the pivot position.
[0040]
Accordingly, the contact position of each cam surface 5b of each swing cam 5 with respect to the upper surface of each valve lifter 6 moves to the cam nose portion 5c side. For this reason, when the drive cam 4 rotates and pushes up one end 10a of the rocker arm 10 via the link arm 11, the lift of the valve lifter 6 relative to the valve lifter 6 increases, as shown in FIG. 8B.
[0041]
Therefore, the valve lift amount L2 of each intake valve 2 increases, so that the opening timing is advanced and the closing timing is delayed. As a result, for example, the intake charge efficiency in a high load region is improved, and a sufficient output can be secured.
[0042]
Further, according to this embodiment, the link arm 11 has the protruding end 11b held in the notch 10d of the one end 10a of the rocker arm 10 so that the movement in the left-right direction is restricted and the ring portion 11a Is supported by the extending portions 27a, 27b, 28a, 28b of the swing cams 5, 5 in a sandwiched state, that is, in a state where the operation of the link arm 11 and each of the swing cams 5, 5 is not hindered. The free movement of the annular portion 11a in the axial direction is restricted. For this reason, the tilting of the link arm 11 is prevented, and a partial contact between the inner peripheral surface of the fitting hole 11c of the annular portion 11a and the outer peripheral surface 4a of the drive cam 4 is prevented.
[0043]
As a result, the occurrence of wear on the inner peripheral surface of the fitting hole 11c and the outer peripheral surface 4a of the driving cam is prevented, and the durability can be improved.
[0044]
Next, the operation of the lubricating oil supply circuit in this embodiment will be described. During the operation of the engine, the lubricating oil supplied into the first oil passage 18 passes through the first communication passage 19 and the inner peripheral surface of the fitting hole 11c and the drive cam 4 as shown in FIGS. Is supplied into the first sliding gap C between the outer peripheral surface 4a and the outer peripheral surface 4a. Therefore, the space between the outer peripheral surface 4a of the drive cam 4 and the fitting hole 11c of the link arm 11 is forcibly lubricated, and the lubrication performance is improved.
[0045]
Therefore, the wear of the annular portion 11a and the driving cam 4 can be effectively prevented in combination with the free movement restriction action of the annular portion 11a in the left-right direction (the axial direction of the drive shaft 3). Can be.
[0046]
Moreover, the lubricating oil flowing out between the inner peripheral surface of the fitting hole 11c and the outer peripheral surface 4a of the drive cam 4 is removed from the outer surface of the annular portion 11a and the extension portions 27a to 28b of the swing cams 5 and 5. The lubricating performance of such a portion is also improved because it is also supplied between the opposite end portion. Further, the lubricating oil supplied to the opposite end drops onto the upper surface of the valve lifter 6, and the lubricating performance between the swing cams 5, 5 and the upper surface of the valve lifter 6 is also improved.
[0047]
On the other hand, the lubricating oil supplied into the second oil passage 20 passes through the diametric hole 21 and the second communication passage 22, and the second sliding gap C2 between the inner surface of the support hole 10c and the outer surface of the control cam 17 Supplied within. Therefore, the space between the control cam 17 and the rocker arm 10 is forcibly lubricated.
[0048]
Further, in this embodiment, since the swing cams 5 and 5 have the base ends 5a and 5a formed separately, the drive shaft 3 and the drive cam 4 can be integrally formed. .
[0049]
That is, when the base end portions 5a, 5a of the swing cams 5, 5 are not formed separately, when assembling the components, the drive shaft 3 is axially extended from both ends of the drive shaft 3 for each cylinder. After the swing cams 5 and 5 are inserted, the drive shaft 3 and the separate drive cam 4 must be fixed with pins or the like, and this assembling work is extremely complicated. However, since the swing cams 5 and 5 are formed separately, even if the drive cam 4 is formed integrally with the drive shaft 3 in advance, the swing cams 5 and 5 must be mounted from the radial direction of the drive shaft 3. You can do it.
[0050]
Therefore, the drive shaft 3 and the drive cam 4 can be integrated, and the overall assembling workability is improved.
[0051]
Further, since the integral projected area (projected diameter) of the integrated drive shaft 3 and drive cam 4 in the axial direction is smaller than the inner diameter of the fitting hole 11c of the link arm 11, the drive shaft 3 and the drive cam 4 Even if the unit 4 is integrated, the link arm 11 can be assembled to the outer peripheral surface 4a of the drive cam 4, and then the swing cams 5, 5 can be assembled from the radial direction. Therefore, the assemblability of these members is improved, and the assembling work efficiency can be improved.
[0052]
FIG. 9 shows a second embodiment of the present invention, in which extending portions 27a, 28a inside the oscillating cams 5, 5 and both side surfaces of the annular portion 11a of the link arm 11 and one outside extending portion. Shims 32, 33, and 34 for gap adjustment are provided between the portion 28b and the inner surface of the one bearing 24.
[0053]
Each of the shims 32, 33, 34 has a different axial length, the inner shims 32, 33 are formed in a substantially annular shape having a short axial length, and the outer shims 34 have an axial length. Are relatively long and formed in a cylindrical shape.
[0054]
That is, by selectively arranging the various shims 32 to 34 having different lengths, the axial lengths of the extension portions 27a to 28b due to molding errors and assembling errors of the components are increased. Even if the swinging cams 5 and 5 cannot be accurately positioned, the shims 32 to 34 are selectively attached to adjust the clearance between the bearings 24 and 24 and the annular portion 11a. It can be performed. Therefore, free movement of the annular portion 11a of the link arm 11 in the axial direction can be reliably restricted.
[0055]
It is to be noted that the shims 32 to 34 may have different lengths in the axial direction as appropriate according to the length of the gap in the axial direction, or may be adjusted after the gap length is measured. Is also possible.
[0056]
Instead of this adjusting shim, a simple spacer having a certain thickness may be used. For example, when the shim 32 is used as a spacer, the end face of the swing cam 5 that swings separately and the side surface of the link arm do not come into direct contact with each other, so that the end face and the side face are prevented from being worn. Further, when the shim 34 is used as a spacer, the side surface of the cylinder head 24 made of aluminum or the like does not directly contact the end surface of the swing cam 5, and wear of the side surface of the bearing 24 is prevented.
[0057]
The technical ideas other than the claims that can be grasped from the embodiment will be described below.
(A) The two swing cams are characterized in that movement in the axial direction is restricted by a drive shaft bearing member having an end surface opposite to the opposed end surface fixed to a cylinder head. A valve train for an internal combustion engine according to claim 1.
[0058]
According to the present invention, since the respective end faces on the outer sides of the swing cams abut against the bearing member, the axial movement is restricted, so that the inadvertent movement of the link arm in the axial direction is more reliably restricted. be able to.
(B) The rocker arm is swingably supported on the outer circumferential surface of an eccentric control cam fixed to the outer circumference of a control shaft, and the swing cam driving an engine valve is provided at the other end via a link rod. On the other hand, by controlling the rotation of the control shaft and the control cam according to the engine operating state, the swing fulcrum of the rocker arm is changed, and the sliding position of the swing cam with respect to the engine valve is changed. 4. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the valve lift amount of the engine valve is changed.
[0059]
The present invention is not limited to the configuration of each of the above-described embodiments, and can be applied not only to the intake valve side but also to the exhaust valve side. It is also possible to apply to a valve train.
[0060]
Further, as the rocker arm, a general rocker arm that directly presses the engine valve at one end can be used.
[Brief description of the drawings]
FIG. 1 is an exploded cross-sectional view showing a valve train according to a first embodiment of the present invention.
FIG. 2 is a side view of the valve train of the embodiment.
FIG. 3 is a plan view of the valve train of the embodiment.
FIG. 4 is a perspective view of the valve train of the present embodiment.
FIG. 5 is a perspective view showing a valve train of the present embodiment.
FIG. 6 is a front view of the valve train of the present embodiment.
FIG. 7A is an operation explanatory view showing a closing operation state of the intake valve at the time of the minimum lift control by the valve train of the embodiment, and FIG. is there.
FIG. 8A is an operation explanatory view showing a closing operation state of an intake valve during maximum lift control by the valve train of the embodiment, and FIG. 8B is an operation explanatory view showing an opening operation state of the intake valve during the maximum lift control. is there.
FIG. 9 is an exploded cross-sectional view showing a valve train according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Intake valve 3 ... Drive shaft 4 ... Drive cam 4a ... Outer peripheral surface 5 ... Swing cam 7 ... Transmission mechanism 8 ... Variable mechanism 10 ... Rocker arm 10a ... One end 10b ... Other end 11 ... Link arm 11a ... Annular portion 11c Fitting hole 18 First oil passage 19 First communication passage 20 Second oil passage 21 Diameter hole 22 Second communication passages 27a and 27b Extensions 28a and 28b Extensions 32-34 ... Sim

Claims (3)

A substantially circular drive cam in which the rotational force of the drive shaft is transmitted, and the shaft center is provided eccentrically with the shaft center of the drive shaft;
A link arm that rotatably holds the drive cam inside the annular portion and converts a rotational force from the drive cam into a reciprocating motion;
A rocker arm that swings by a driving force transmitted from the link arm;
A valve gear for an internal combustion engine, comprising: a pair of swing cams that are swingably supported by the drive shaft and swing by a swing power transmitted from the rocker arm to drive an engine valve.
The two oscillating cams are arranged on both sides of the drive cam, and the annular portion of the link arm is supported between opposite end surfaces of the two oscillating cams so as to be sandwiched from both axial sides of the drive shaft. Valve device for an internal combustion engine. The valve gear of an internal combustion engine according to claim 1, wherein a shim is provided between at least one of the opposing end surfaces of the two swing cams and the link arm. 3. The valve train for an internal combustion engine according to claim 1, wherein a lubricating oil supply circuit that supplies lubricating oil is provided between the drive cam and the annular portion from inside the drive shaft. 4.

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