JPH11336521A - Variable valve system of internal-combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compact the whole construction and enlarge the lift of a valve by suppressing the transverse dimension of the system while variably controlling the valve timing and the lift. SOLUTION: This variable valve system is equipped with a rocker arm 18 swinging through a link arm 19 with rotation of a drive cam 15 and a swing cam 17 to open and close a suction valve 12 through a link member 20 with swings of the rocker arm 18, whereby the valve lift is changeable using a changing mechanism 21 which changes the position where the swing cam 17 contacts with the top face of a valve lifter 16. An eccentric member 14 is installed between the drive shaft 13 and swing cam 17, and by an eccentric bushing 30 on the member 14, the center of swinging Z of the cam 17 is offset for a specified amount β toward the base circle plane 25a from the axis Q of the valve lifter 16 so that the traveling amount relative to the top 16a of the cam face 25 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve operating apparatus for an internal combustion engine which can change the opening / closing timing (valve timing) and valve lift of an intake / exhaust valve in accordance with the operating state of the engine.

[0002]

2. Description of the Related Art As is well known, the intake air / fuel ratio is improved in order to improve fuel efficiency at low engine speed and low load, to ensure stable driving performance, and to secure sufficient output by improving intake air charging efficiency at high speed and high load. Various valve operating devices for variably controlling the opening / closing timing of an exhaust valve and the valve lift amount according to the engine operating state have been conventionally provided.
It is known from Japanese Patent No. 37305 or the like.

Referring to FIG. 15, the camshaft 2 is provided at a position substantially above the center of the upper deck of the cylinder head 1 and a cam 2a is integrally provided on the outer periphery of the camshaft 2. ing. Also,
A control shaft 3 is disposed parallel to a side portion of the camshaft 2, and a rocker arm 5 is pivotally supported on the control shaft 3 via an eccentric cam 4. on the other hand,
A swing cam 8 is disposed at the upper end of an intake valve 6 slidably provided on the cylinder head 1 via a valve lifter 7. The swing cam 8 is swingably supported by a support shaft 9 disposed above the valve lifter 7 and in parallel with the camshaft 2, and a cam surface 8 a at the lower end is in contact with the upper surface of the valve lifter 7. . Further, the rocker arm 5 has one end 5a in contact with the outer peripheral surface of the cam 2a and the other end 5b in contact with the upper end surface 8b of the swing cam 8, so that the cam 2
The lift a is transmitted to the intake valve 6 via the swing cam 8 and the valve lifter 7.

The rotation of the control shaft 3 is controlled within a predetermined angle range by an actuator (not shown) to control the rotation position of the eccentric cam 4, thereby changing the swing fulcrum of the rocker arm 5. ing.

[0005] When the eccentric cam 4 is controlled to a predetermined forward / reverse rotation position, the swing fulcrum of the rocker arm 5 changes, and
The contact position of the other end portion 5b with the upper end surface 8b of the swing cam 8 changes in the vertical direction in the drawing, whereby the contact position of the cam surface 8a of the swing cam 8 with the upper surface of the valve lifter 7 changes. By changing the swing trajectory of the swing cam 8, the opening / closing timing (valve timing) of the intake valve 6 and the valve lift amount are variably controlled. Incidentally, 10 in the figure
Is a spring that constantly biases the upper end surface 8b of the swing cam 8 against the other end 5b of the rocker arm 5.

[0006]

However, in the conventional valve train, the cam 2a and the swing cam 8 are provided on the camshaft 2 and the support shaft 9, respectively.
Numerals 8 are separately and independently arranged at positions largely separated in the width direction of the engine. For this reason, a large arrangement space for the cam 2a and the swing cam 8 is required.

Since the cam 2a and the oscillating cam 8 are largely separated in the width direction of the engine, both ends 5
a, 5b must inevitably extend substantially in the width direction of the engine. Therefore, the rocker arm 5 is increased in size in conjunction with the increase in the arrangement space, so that the mountability of the valve train on the engine is deteriorated, and the engine is increased in size and weight is inevitable.

Further, since the support shaft 9 is required in addition to the camshaft 2, the number of parts is increased, and the axial centers of the camshaft 2 and the support shaft 9 are easily shifted from each other. Timing control accuracy may be reduced.

Further, since the rocker arm 5 is configured so that the end 5b of the rocker arm 5 directly rocks the upper end surface 8b of the rocker cam 8, the rocker arm 5 is rocked. ) May be detached from the upper end surface 8b of the swing cam 8. Therefore, the position of the swing fulcrum of the rocker arm 5 is restricted, and the swing trajectory of the swing cam 8 and thus the valve timing / lift amount of the intake valve 6 cannot be set large.

[0010]

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems of the above-mentioned conventional variable valve operating system, and has the following features.
The described invention is rotationally driven by the crankshaft of the engine,
A drive shaft having a drive cam fixed to the outer periphery, a swing cam provided to be swingable on the drive shaft, and opening and closing an engine valve via a valve lifter; and a drive cam having one end portion provided with a link arm. A rocker arm rotatably linked to the other end and the other end linked to the end of the rocking cam, a variable mechanism for changing the rocking fulcrum of the rocker arm, and operation control of the variable mechanism according to the engine operating state. Valve means for variably controlling the swing fulcrum of the rocker arm to change the swing position of the swing cam with respect to the top surface of the valve lifter to variably control the lift amount of the engine valve. The swing center of the swing cam is arranged so as to be offset by a predetermined amount toward the base circle side of the swing cam with respect to the axis of the valve lifter.

According to a second aspect of the present invention, an eccentric member for offsetting the swing center of the swing cam is provided on the eccentric bush interposed between the drive shaft and the swing cam, and protruding from the eccentric bush. And an arm portion having a distal end portion fixed to the cylinder head.

According to a third aspect of the present invention, an eccentric member for offsetting the swing center of the swing cam is provided on the eccentric bush interposed between the drive shaft and the swing cam, and protruding from the eccentric bush. The distal end is constituted by an arm engaged with a control shaft of the variable mechanism.

According to a fourth aspect of the present invention, the axis of the drive shaft and the center of swing of the swing cam are set to be the same, and the center of swing of the swing cam is set at a base with respect to the axis of the valve lifter. It is characterized by being arranged so as to be offset to the circle side.

[0014]

1 to 4 show a first embodiment of a variable valve apparatus according to the present invention, which is applied to an internal combustion engine having two intake valves per cylinder. .

That is, the variable valve apparatus includes a pair of intake valves 12, 12 slidably provided on a cylinder head 11 via a valve guide (not shown), and a cylinder head 1.
(1) a hollow drive shaft 13 rotatably supported by a bearing (not shown) at the top, a pair of drive cams 15, 15 fixedly mounted on the outer peripheral surface of the drive shaft 13 by press fitting or the like; 13
A pair of swing cams 17, 17 are provided rotatably to open and close the intake valves 12, 12 via valve lifters 16, 16, and one end 18 a is a pair of link arms 19, 19. A pair of rocker arms 18, 18, each of which is linked to the driving cams 15, 15 via a link member 20, and the other end 18 b is linked to the rocking cam 17, 17 via a link member 20, 20. It mainly comprises a variable mechanism 21 for changing the position of the swing fulcrum 18 and a control means (not shown) for controlling the operation of the variable mechanism 21 according to the operating state of the engine.

The drive shaft 13 is disposed along the longitudinal direction of the engine, and is driven by a crank of the engine via a driven sprocket (not shown) provided at one end and a timing chain wound around the driven sprocket. Torque is transmitted from the shaft.

As shown in FIG. 4, each of the driving cams 15 has a substantially cylindrical shape, and has a large-diameter cam main body 15a and a cylindrical portion 15b integrally provided on a side end surface of the cam main body 15a. And a drive shaft press-fitting hole 15c is formed in the inner axial direction, and the axis X of the cam body 15a is
3 is offset in the radial direction by a predetermined amount. Further, the drive cam 15 is press-fitted and fixed to the drive shaft 13 on both outer sides not interfering with the valve lifters 16, 16 via a drive shaft press-fit hole 15 c. A portion located between the two swing cams 17 is supported by a bearing 22.

Each of the valve lifters 16 is shown in FIGS.
A cylindrical skirt portion 16 having a closed cylindrical shape as shown in FIG.
a and an upper wall integrally formed at the upper end of the skirt portion 16a. The skirt portion 16a is slidably held in holding holes 11a, 11a formed in the cylinder head 11, while the upper wall is Is formed in an arc shape along the direction orthogonal to the drive shaft 13.

Each of the link arms 19 has an annular base 19a having a relatively large diameter and a protruding end 19b protruding at a predetermined position on the outer peripheral surface of the base 19a.
In the center of the drive cam 15, there is formed a fitting hole 19c which is rotatably fitted to the outer peripheral surface of the cam body 15a, while the projecting end 19b is provided with a pin through which the pin 23 is rotatably inserted. A hole 19d is formed through.

Each of the swing cams 17 has a substantially horizontal U-shape as shown in FIGS. 1 and 4, and has a large-diameter insertion hole into which a pair of eccentric members 14, 14 are rotatably inserted. 1
7a and 17a are formed through each cam nose portion 24 located on the other end portion 18b side of each rocker arm 18.
A pin hole 24a is formed through the side. A cam face 25 is formed on the lower surface of each swing cam 17. Each of the cam faces 25 has an arc-shaped base circular surface 25a that is revered at one end side, and a cam surface 25b that extends from the base circular surface 25a to the end of the cam nose portion 24 in an arc shape.
And a cam lift portion 25 provided on the tip side of the cam surface 25b.
c, the base circular surface 25a and the cam surface 25
b and the cam lift portion 25c abut on a predetermined position on the upper surface of each valve lifter 16 according to the swing position of the swing cam 17. That is, from the viewpoint of the valve lift characteristics shown in FIG. 5, the predetermined angle range θ1 of the base circular surface 25a becomes the base circle section as shown in FIG.
The predetermined angle range θ2 of 5b is a so-called ramp section,
Further, a predetermined angle range θ3 from the cam surface 25b to the cam lift portion 25c is set to be a lift section.

Each of the eccentric members 14, 14 is shown in FIGS.
The eccentric bush 30 includes a cylindrical eccentric bush 30 and an arm 31 provided integrally with an end of the eccentric bush 30 as shown in FIG. The eccentric bush 30 has a drive shaft 13 therein.
A sliding hole 30a through which the rotary cam slides is formed, and the outer diameter is set to be slightly smaller than the inner diameter of the insertion hole 17a of the swing cam 17, and the swing cam 17 is swingably supported. . The eccentric bush 30 has a thick portion 30b as shown in FIG.
The swing center 17 of the swing cam 17 is arranged on the center left side by a predetermined amount β toward the base circle surface 25a (base circle) side from the extension line of the axis Y of the drive shaft 13, that is, the axis Q of the valve lifter 16. Offset arrangement. On the other hand, the arm 31
The tip portion has a horizontal flat plate shape, and is fixed to the upper end portion of the cylinder head 11 by a bolt 32 inserted into a bolt hole 31a formed at the center of the tip portion. Therefore, the swing cam 17 is stably supported by the cylinder head 11 by the eccentric member 14.

The bearing 22 is provided at the upper end of the cylinder head 11 as shown in FIGS.
And a sub-bracket 22b provided at an upper end portion of the main bracket 22a and rotatably supporting a control shaft described later. Brackets 22a, 22
b is fixedly fastened to the cylinder head 11 from above by a pair of bolts 22c, 22c.

Each rocker arm 18 is shown in FIGS.
As shown in FIG.
3 is disposed along the engine width direction, a base 18c provided at the center is swingably supported by a control shaft 28 described later, and one end 18a is connected to the pin 23.
The other end 18b is rotatably connected to one end 20a of the link member 20 via a pin 26 while being rotatably connected to the protruding end 19b of the link arm 19 via a pin 26.

Each of the link members 20 is formed in a straight line having a predetermined length as shown in FIG.
Reference numerals a and 20b are rotatably connected to the other end 18b of the rocker arm 18 and one end 24 of the swing cam 17 via pins 26 and 27, respectively.

The ends of each of the pins 23, 26 and 27 have
Snap rings 31 are provided to restrict the axial movement of the link arm 19 and the link member 20, respectively.

The variable mechanism 21 includes a control shaft 28 supported between the main bracket 22a and the sub-bracket 22b of the bearing 22, and a cam hole press-fitted and fixed to the control shaft 28 and provided in a base 18c of the rocker arm 18. 18
d, and a control cam 29 rotatably fitted in the housing d.

Each of the control cams 29 has a substantially cylindrical shape, and has an insertion hole 29a which is inserted into the control shaft 28 in the inner axial direction and is press-fitted and fixed therein.
1 deviates from the axis P of the control shaft 28 by α.

The control shaft 28 is controlled by an electromagnetic actuator (not shown) provided at one end so as to rotate within a predetermined rotation angle range. The electromagnetic actuator is a control means for detecting an operating state of the engine. Is driven by a control signal from a controller (not shown). The controller detects a current engine operation state by calculation or the like based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a water temperature sensor, and outputs a control signal to the electromagnetic actuator.

In the following, the operation of the present embodiment will be described. First, when the engine is at low speed and low load, the electromagnetic actuator is driven to rotate to one side by a control signal from the controller.
Accordingly, the control shaft 28 is also rotated by a predetermined amount in the same direction, and the control cam 29 is moved from the axis P of the control shaft 28 to the upper left rotation position as shown in FIGS. The thick portion 29b is held and moved upward away from the drive shaft 13. Accordingly, the entire rocker arm 18 moves upward with respect to the drive shaft 13, and pulls the link member 20 upward by the other end 18b. Therefore, the swing cam 17,
At 17, one end 24 is forcibly pulled up slightly and the whole is held in a counterclockwise rotation position as shown.

Therefore, when one end 18a of each rocker arm 18 is operated in the vertical direction via each link arm 19 by the rotation of each drive cam 15, each rocker arm 18 swings with the control cam 29 as a swing fulcrum. , Other end 1
8b transmits the oscillating power to each oscillating cam 17 via each link member 20. Each swing cam 17 has a base circular surface 25.
a, the cam surface 25b, and the cam lift portion 25c are pressed or released while sliding on the top surface 16c of the valve lifter 16 to open or close each intake valve 12. The lift amount L1 is as shown in FIG. Relatively small.

Therefore, in such a low-speed and low-load region, the valve lift amount becomes small, the opening timing of each intake valve 12 becomes late, and the valve overlap with the exhaust valve becomes small. For this reason, improvement in fuel consumption and stable rotation of the engine can be obtained.

On the other hand, when the engine shifts to high engine high load, the electromagnetic actuator is driven to rotate in the opposite direction by the control signal from the controller. Therefore, as shown in FIGS. 8 and 9, the control shaft 28 rotates clockwise by a predetermined amount (in the direction of the arrow in the figure) to move the control cam 29 by a predetermined amount in the counterclockwise direction from the position shown in FIGS. Rotate the shaft center P1
(Thick portion 29b) is moved downward. For this reason, each rocker arm 18 moves in the direction of the drive shaft 13 as a whole, and the other end 18 b pushes one end 24 of each swing cam 17 downward via each link member 20, The entire swing cam 17 is rotated clockwise by a predetermined amount.

Therefore, the contact position of each swing cam 17 with respect to the upper surface of the valve lifter 16 moves to the right position on the one end 24 side as shown in FIGS. Therefore, when the drive cam 15 rotates to swing the rocker arm 18 to swing the swing cams 17, 17 within a predetermined range, the lift amount L2 of the valve lifter 16 with respect to the valve lifter 16 increases as shown in FIG. 9B.

Therefore, in such a high-speed high-load region, the cam lift characteristics are larger than those in the low-speed low-load region, so that the valve lift is increased. In addition, the opening timing of each intake valve 12 is advanced while the closing timing is delayed. Become. As a result, the intake charging efficiency is improved, and a sufficient output can be secured. As described above, the opening / closing timing of each intake valve 12 and the valve lift can be made variable according to the engine operating state.

In this embodiment, since the swing fulcrum Z of each swing cam 17 is offset from the axis Q of the valve lifter 16 by a predetermined amount γ, the valve of the cam face 25 of each swing cam 17 is disposed. The area of the lifter 16 that slides on the top surface 16b is enlarged, and the lifter 16 can slide over almost the entire top surface 16b. Therefore, the swing cam 1
7, the travel area on the top surface 16b by the cam face 25 is increased. That is, the swing fulcrum Z of the swing cam 17
Are arranged on the same line in the vertical direction without offsetting with respect to the axis Q of the valve lifter 16,
Since only about half of the top of the valve lifter 16b on the right side in FIG. 1 is used for sliding contact with the swing cam 17, the swing amount is naturally restricted, and a sufficient valve lift of the intake valve 12 is obtained. There was a problem that there was no. However, if the swing fulcrum Z is offset from the axis Q of the valve lifter 16 toward the base circular surface 25a as described above, the cam face 2
5 can be brought into sliding contact with almost the entire top surface 16b of the valve lifter 16, so that a large travel area of the swing cam 17 with respect to the valve lifter top surface 16b can be obtained without increasing the swing angle. Therefore, the intake valve 1
2, the valve lift can be increased.

Moreover, since a large travel amount can be obtained without increasing the outer diameter of the valve lifter 16, the outer diameter of the valve lifter 16 can be made as small as possible. And the overall structure can be reduced in size.

Further, the top surface 16 of each valve lifter 16
Since b is formed in an arc shape in the swing direction of the swing cam 17, the travel area of the cam face 25 with respect to the top surface 16b of each swing cam 17 can be further increased. As a result, if the top surface 16b has the same valve lift as the horizontal plane, the swing angle of the swing cam 17 can be reduced in conjunction with the increase in the valve lift due to the offset arrangement of the swing cam 17. Therefore, the size of each link mechanism such as the link arm 19 and the link member 20 can be reduced, and the entire apparatus can be downsized.

Further, according to this device, since the drive cam 15 and each swing cam 17 are provided on the drive shaft 13 substantially coaxially, the arrangement space in the engine width direction can be sufficiently reduced.

The drive cam 15 is formed in a ring shape, and the entire outer peripheral surface is formed in the fitting hole 19 of the link arm base 19a.
Since the entire inner peripheral surface of c is in sliding contact, the surface pressure on the outer peripheral surface is dispersed and the surface pressure can be sufficiently reduced. Therefore, the occurrence of wear between the inner peripheral surfaces of the fitting holes 19c can be suppressed, and
Easy lubrication. In addition, the driving cam 1
The degree of freedom in selecting the material of No. 5 is improved, and a material which is easy to process and can be selected at low cost can be selected.

Further, since the present apparatus employs a so-called 6-link system as a whole, it is possible to increase the rocker ratio of the rocker arm 18, thereby avoiding setting a large offset amount of the drive cam 15 with respect to the drive shaft 13. Even if the outer diameter of the driving cam 15 is not set large, a large swing angle of the swing cam 17 can be obtained. As a result, the overall size of the apparatus can be further reduced.

Further, since the rocker arm 18 and the swing cam 17 are linked via the link member 20, even if the rocker ratio of the rocker arm 18 is set to a relatively large value, the link between the rocker arm 18 and the swing cam 17 is set. The state is always maintained. Accordingly, a large swing angle of the swing cam 17 is obtained, so that the ramp section θ2 of the swing cam 17 can be increased, thereby reducing the collision speed between the valve lifter 16 and the swing cam 17. As a result, it is possible to suppress the generation of driving noise.

Further, the present apparatus has two intake valves 12, 1
The control shaft 28 can also be supported together with the bearing 22 provided between the cylinder heads 2, so that it can be mounted as it is on a conventional internal combustion engine.
1 does not require a change in shape, and can prevent a rise in manufacturing cost. In addition, since the drive shaft 13 can be located at the same position as in the related art, it is not necessary to change the shape of the cylinder head 11 in this respect as well.

Further, in the present apparatus, since the rocker arm 18 is merely disposed at a position above the drive shaft 13, the overall height can be sufficiently reduced.

FIGS. 10 to 12 show a second embodiment of the present invention, in which the configuration of the eccentric member 14 is changed. That is, the eccentric member 14 is formed by the drive shaft 13 and the swing cam 1.
An eccentric bush 33 interposed between the eccentric bush 33 and an arm portion 34 integrally provided at an end of the eccentric bush 33.
The structure of the arm 3 is the same as that of the first embodiment, but the arm 34 has a simple flat plate shape, extends in the vertical direction, and has a substantially U-shaped engaging portion formed at the tip. Mating groove 34
a slidably engages the control shaft 28 from below, and functions as a detent for the eccentric bush 33.

Therefore, according to the present embodiment, the eccentric member 14 can provide the same operation and effect as those of the first embodiment described above. Only by engaging the engaging groove 34a with the control shaft 28, the structure of the arm portion 34 is extremely simplified, and the efficiency of the manufacturing operation and the ease of assembly are improved.

Further, since the rotation is prevented only by engaging the engagement groove 34a with the control shaft 28, the precision of the engagement groove 34a of the arm portion 34 with respect to the center of the insertion hole 33a of the drive shaft of the eccentric bush 33 is high. No special processing is required, and this also facilitates production.

FIG. 13 shows a third embodiment of the present invention.
The swing center Z of the swing cam 17 is set to be the same as the axis Y of the drive shaft 13, and the swing center Z of the swing cam 17 is set to the base circular surface 25 a ( The base circle) is offset. That is, the arrangement of the entire swing cam 17 including the drive shaft 13 is changed, and the swing center Z (perpendicular line R) of the swing cam 17 is offset from the axis Q of the valve lifter 16 by a predetermined amount δ. Things. Therefore, the oscillating cam 17 is provided with the cam face 25 and the flat top surface 16 of the valve lifter 16.
Sliding contact can be made over almost the entirety of b, which increases the travel area, so that the valve lift can be similarly increased.

Here, the intake valve 12 is arranged so that its axis is coaxial with the axis Y of the drive shaft 13, that is, the perpendicular R.

FIG. 14 shows a fourth embodiment of the present invention.
As in the third embodiment, the swing center Z (perpendicular line R) of the swing cam 17 is offset from the axis Q of the valve lifter 16 by a predetermined amount δ toward the base circular surface 25a (base circle). It is. Therefore, the same operation and effect as those of the third embodiment can be obtained, and the outer diameter of the valve lifter 16 can be reduced by arranging the axis of the intake valve 12 coaxially with the axis Q of the valve lifter 16. it can. As a result, the thickness of the partition wall of the cylinder head 11 between the valve lifters 16 can be increased, and vibration accompanying the improvement in strength can be suppressed.

The present invention is not limited to the configuration of each of the above embodiments. For example, the present apparatus can be applied to the exhaust valve side or both the intake and exhaust valve sides. It is also possible to apply to one valve instead of a valve.

[0051]

As apparent from the above description, according to the present invention, not only the valve timing and the valve lift of the engine valve can be variably controlled, but also the drive cam and the swing cam are combined with the drive shaft. The arrangement space in the engine width direction can be made sufficiently small, and the rocker arm does not need to be extended in the engine width direction, so that the entire apparatus can be made compact. As a result, the mountability of the device on the engine is improved.

Further, by providing the swing cam together with the eccentric cam on the drive shaft, a special support shaft as in the prior art is not required, so that the number of parts can be reduced and the drive shaft and the swing cam can be combined. Since the mutual center accuracy is easily obtained, it is possible to prevent a decrease in valve timing control accuracy.

Further, according to the present invention, since the swing center of the swing cam is offset toward the base circle with respect to the axis of the valve lifter, the travel area of the swing cam relative to the top surface of the valve lifter is increased, and the engine valve of the engine valve is increased. It is possible to increase the valve lift. As a result, the engine performance according to the operating state can be sufficiently exhibited, and conversely, if the valve lift is the same, the swing angle of the swing cam can be reduced, so that the entire apparatus can be downsized. The freedom of layout on the institution is improved, and the mountability is improved.

According to the second aspect of the present invention, since the eccentric means is fixed to the cylinder head, the swing cam can be stabilized, and the control accuracy of the valve timing can be prevented from lowering.

According to the third aspect of the invention, the structure of the eccentric means is simplified, and the efficiency of the manufacturing operation and the efficiency of the assembly operation can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention as viewed from the direction indicated by an arrow A in FIG.

FIG. 2 is a side view showing a partial cross section of the embodiment.

FIG. 3 is a plan view of the embodiment.

FIG. 4 is an exploded perspective view of each component provided in the embodiment.

FIG. 5 is a valve lift characteristic diagram corresponding to a base end surface and a cam surface of an oscillating cam.

FIG. 6A shows the valve closing action at low speed and low load.
Arrow view.

FIG. 7 shows the valve opening action at low speed and low load.
Arrow view.

FIG. 8A shows the valve closing action at the time of high speed and high load.
Arrow view.

FIG. 9A shows the valve opening action at the time of high speed and high load.
Arrow view.

FIG. 10 is a perspective view showing an eccentric means provided in a second embodiment of the present invention.

FIG. 11 is a sectional view of a main part of the embodiment.

FIG. 12 is a side view of a main part of the embodiment.

FIG. 13 is a front view of an essential part showing a third embodiment of the present invention.

FIG. 14 is an essential part front view showing a fourth embodiment of the present invention.

FIG. 15 is a sectional view showing a conventional variable valve operating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Cylinder head 12 ... Intake valve 13 ... Drive shaft 14 ... Eccentric member 15 ... Drive cam 16 ... Valve lifter 16c ... Top surface 17 ... Swing cam 18 ... Rocker arm 18a ... One end 18b ... Other end 19 ... Link arm 20 ... Link member 21 ... Variable mechanism 24 ... Cam nose part (end part) 25 ... Cam face 25a ... Base circle surface (base circle) 30,33 ... Eccentric bush 31,34 ... Arm part Z ... Swinging fulcrum of swing cam

Continuing from the front page (72) Inventor Shin Nakamura 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd.

Claims (4)

[Claims] 1. A rotary drive by a crankshaft of an engine,
A drive shaft having a drive cam fixed to the outer periphery, a swing cam provided to be swingable on the drive shaft, and opening and closing an engine valve via a valve lifter; and a drive cam having one end portion provided with a link arm. A rocker arm rotatably linked to the other end and the other end linked to the end of the rocking cam, a variable mechanism for changing the rocking fulcrum of the rocker arm, and operation control of the variable mechanism according to the engine operating state. Valve means for variably controlling the swing fulcrum of the rocker arm to change the swing position of the swing cam with respect to the top surface of the valve lifter and variably controlling the lift amount of the engine valve. Wherein the swing center of the swing cam is arranged so as to be offset by a predetermined amount toward the base circle of the swing cam with respect to the axis of the valve lifter. Valve device. 2. An eccentric member for offsetting an oscillating center of an oscillating cam, an eccentric bush interposed between a drive shaft and the oscillating cam, and a tip end protruding from the eccentric bush and having a cylinder head. 2. The variable valve train for an internal combustion engine according to claim 1, wherein said variable valve train comprises an arm fixed to said arm. 3. An eccentric member for offsetting the oscillating center of the oscillating cam, an eccentric bush interposed between a drive shaft and the oscillating cam; 2. A variable valve operating apparatus for an internal combustion engine according to claim 1, wherein said variable valve operating apparatus comprises an arm engaged with a control shaft of said variable mechanism. 4. The apparatus according to claim 1, wherein the axis of the drive shaft and the center of swing of the swing cam are set to be the same, and the center of swing of the swing cam is offset toward the base circle with respect to the axis of the valve lifter. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein