JP2000234508A - Variable valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve control responsiveness and to reduce size of an actuator by reducing unbalanced load torque caused by force of a valve spring and exerted on a control shaft. SOLUTION: This device operates an intake valve 12 for opening against force of spring of a valve spring 10 by an oscillation cam 17 which links to a rocker arm by oscillating the rocker arm through a link arm by a driving cam fixed on a driving shaft 13. The device is provided with a bias mechanism which exerts force against one side torque working on a control shaft from the valve spring 10 through the rocker arm and a control cam by pressing a projecting part 41 with force of spring of a valve spring 45 through a plunger 44.

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 vary a valve lift of an intake valve or an exhaust valve according to an operating state of the engine.

[0002]

2. Description of the Related Art Conventional variable valve gears of this type include:
Some are described in Japanese Patent Application Nos. 9-212831 and 10-297711 filed earlier by the present applicant.

Referring to FIG. 12, this variable valve apparatus is applied to an intake valve side, and has a shaft center on an outer periphery of a drive shaft 51 which rotates in synchronization with rotation of a crankshaft. A drive cam 52 whose Y is eccentric from the axis X of the drive shaft 51 is provided, and the rotational force of the drive cam 52 is transmitted via a multi-node link transmission mechanism to the upper end of the intake valve 53. A cam surface 55 slidably contacts an upper surface of the valve lifter 54 having a swing cam 56 for opening the intake valve 53 against the spring force of the valve spring 65.

The transmission mechanism includes a rocker arm 58 disposed above a swing cam 56 and supported by a control shaft 57 so as to be swingable, and an annular one end 59a fitted on the outer peripheral surface of the drive cam 52. A link arm 59 whose other end 59b is rotatably connected to one end 58a of the rocker arm 58 via a pin 60, and one end 61a is rotatably connected to the other end 58b of the rocker arm 58 via a pin 62. A link rod 6 whose other end 61b is rotatably connected to a cam nose portion 56a of the swing cam 56 via a pin 63.
And 1.

A control cam 64 having an axis P1 eccentric from the axis P2 of the control shaft 57 by a predetermined amount α is fixed to the outer peripheral surface of the control shaft 57. This control cam 64
A support hole 58c formed substantially at the center of the rocker arm 58
The swing cam 5 is rotatably fitted and held in the swing cam 5 by changing the swing fulcrum of the rocker arm 58 according to the rotation position.
By changing the rolling contact position of the cam surface 55 with 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 in a low rotation and low load range, as shown in FIG. 12, the control shaft 57 is rotated in the other direction by an actuator (not shown), and the control cam 64 is also rotated in the same direction. The rocker arm 5
8 is moved in a direction away from the drive shaft 51. Thereby, the rocker arm 58 and the link rod 6
The pivot point 1 moves upward to raise the cam nose portion 56a of the swing cam 56, whereby the contact position of the swing cam 56 on the upper surface of the valve lifter 54 moves in a direction away from the lift portion 55c. Therefore, the intake valve 53
The valve lift is controlled to be minimized.

Therefore, the engine performance can be sufficiently exhibited in accordance with the engine operating state, that is, the fuel efficiency and the output can be improved.

On the other hand, when the vehicle shifts from the middle rotation middle load region to the high rotation high load region, the control shaft 57 is rotated in the direction indicated by a broken arrow (counterclockwise) by an actuator (not shown), and the control cam 64 is moved in the same direction. As shown in the figure, the rocking fulcrum of the rocker arm 58 moves in the direction approaching the drive shaft 51 as shown in FIG. Thereby, the swing cam 56 is connected to the link rod 6.
The end 56a is pushed down by 1 or the like, and the contact position on the upper surface of the valve lifter 54 moves to the lift portion 55c side, so that the valve lift of the intake valve 53 is controlled to increase.

[0009]

However, in the above-described conventional variable valve apparatus, the swing lift of the rocker arm 58 is changed in accordance with the rotational position of the control cam 64 by the control shaft 57 to thereby increase the valve lift. However, the rotational driving load due to the offset load torque of the valve spring 65 acting on the control shaft 57 has not been sufficiently considered.

[0010] That is, as shown in FIG. 12, the spring reaction force of the valve spring 65 is a force of an arrow F _S to the cam nose portion 56a side of the rocking cam 56 from the valve lifter 54, further link rod 61 and the rocker arm 58
Of the pin 62 (the pivot point Z)
1) Arrow F in a straight line direction passing through the center of the link rod 61
While the force as _R acts, the pressing force due to the eccentric rotational force of the drive cam 52 is applied to the link arm 59 and the rocker arm 58.
Of the pin 60 (the pivot point Z)
2), a force indicated by an arrow Fa acts in a direction of a straight line (Q) connecting the axis (Z2) and the axis X of the drive shaft 51. Therefore, the resultant force (Fc) of F _R and Fa is applied to the control cam 64.
Works. The resultant force Fc is applied to the axis P1 of the control cam 64 offset from the axis P2 of the control shaft 57 by F
This acts as a load torque (rotation moment) for rotating the control cam 64 clockwise in the same direction as that of the control cam 64 in FIG. For this reason, an offset load torque (rotational moment) is also generated in the control shaft 57 in the clockwise direction.

The offset load torque (rotational moment) is:
As shown in FIG. 11A from which the peak torque is extracted, the axis P1 of the control cam 64 becomes maximum during the minimum valve lift control away from the axis P2 of the control shaft 57. For this reason,
When the control shaft 57 rotates from the rotation position of the minimum valve lift control in the arrow direction shown in FIG. 12 to control the valve lift to the maximum valve lift, the resultant force FC acts in the clockwise direction opposite to the arrow rotation direction. Therefore, the rotational load in the counterclockwise direction in the figure increases, and the control responsiveness to the maximum valve lift decreases.

Therefore, in order to improve the control response,
It is necessary to increase the output capacity of the actuator, which necessitates an increase in the size of the actuator. As a result, the weight is increased, the mountability in the engine room is deteriorated, and the cost is increased.

[0013]

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation of the above-mentioned conventional variable valve operating system, and is claimed in claim 1.
According to the invention described above, a drive shaft that rotates in synchronization with the crankshaft of the engine and has a drive cam on the outer periphery, a swing cam that opens the engine valve against the spring force of the valve spring, and one end portion A rocker arm, the other end of which is linked to the swing cam, and a control shaft for swingably supporting the rocker arm via an eccentric control cam;
A variable valve apparatus for an internal combustion engine that controls a rotation position of the control shaft according to an engine operating state to change a swing fulcrum position of a rocker arm to variably control a lift amount of an engine valve.
A bias mechanism is provided which applies a force opposing a one-way rotational force caused by an unbalanced load torque applied to the control shaft via the rocker arm and the control cam by the spring force of the valve spring.

According to a second aspect of the present invention, the bias mechanism is provided integrally with the end of the control shaft in the axial direction, and the axis is eccentric from the axis of the control shaft; A cylinder formed in a right angle direction, a plunger slidably provided in the cylinder and abutting on the protrusion from a direction substantially perpendicular to the axis, and rotating the protrusion by the biased load torque via the plunger. A spring member for urging in a direction opposite to the force direction.

The invention according to claim 3 is characterized in that a block is rotatably provided on the projection, and a tip end of the plunger is elastically contacted with a lower end surface of the block via a spring member.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a variable valve apparatus according to an embodiment of the present invention. The variable valve apparatus of this embodiment includes two intake valves per cylinder, and a variable mechanism that varies a valve lift amount of the intake valve according to an engine operating state.

That is, as shown in FIGS. 1 to 3, this variable valve apparatus is slidably provided on a cylinder head 11 via a valve guide (not shown).
A pair of intake valves 1 urged in the closing direction by 0, 10
A hollow drive shaft 13 rotatably supported by a bearing 14 above the cylinder head 11;
A drive cam 15 fixed by press fitting or the like to the drive shaft 13
Swingably supported by the outer peripheral surface 13a of each intake valve 1
Valve lifters 16, 1 arranged at the upper end of 2, 12
6, two oscillating cams 17 and 17 for opening the respective intake valves 12 and 12 in sliding contact with each other, and a driving cam 15 and oscillating cams 17 and
And a transmission mechanism 18 for transmitting the rotational force of the driving cam 15 as the oscillating power of the oscillating cams 17 and 17
And the variable mechanism 1 for changing the operating position of the transmission mechanism 18
9 and a bias mechanism 40 for applying a bias force to the variable mechanism 19.

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. A rotational force is transmitted from the shaft, and the rotational direction is set counterclockwise in FIG.

The bearing 14 is provided at the upper end of the cylinder head 11 and supports the upper part of the drive shaft 13. The main bracket 14a is provided at the upper end of the main bracket 14a to freely rotate a control shaft 32 which will be described later. And a sub-bracket 14b for supporting the two brackets 14a,
14b is fixed together from above by a pair of bolts 14c, 14c.

As shown in FIG. 4, the driving cam 15 has a substantially ring shape, and has an annular cam body 15a,
A cylindrical portion 1 integrally provided on an outer end surface of the cam body 15a;
5b, the drive shaft insertion hole 15c is formed in the inner axial direction, and the axis Y of the cam body 15a is offset from the axis X of the drive shaft 13 by a predetermined amount in the radial direction. Each of the drive cams 15 is press-fitted and fixed to both sides of the drive shaft 13 via the drive shaft insertion holes 15c so as not to interfere with the valve lifters 16, 16, and the outer peripheral surface 15d of the cam main body 15a is fixed to the drive cam 15. An eccentric cam profile is formed.

The valve lifters 16, 16 are formed in a cylindrical shape with a lid, are slidably held in holding holes of the cylinder head 11, and have upper surfaces 16a, 16a with which the swing cams 17, 17 are in sliding contact. It is formed in a flat shape.

The swing cam 17 has a substantially raindrop shape as shown in FIG.
A support hole 20a, which is inserted and rotatably supported, is formed through, and a pin hole 21a is formed through one end of the cam nose 22 side. In addition, the swing cam 1
7, a cam surface 22 is formed on the lower surface, a base circular surface 22a on the base end portion 20 side, a ramp surface 22b extending in an arc shape from the base circular surface 22a to the cam nose portion 21 side, and a cam nose portion from the ramp surface 22b. The lift surface 22c is formed so as to be continuous with the top surface 22d of the maximum lift provided at the distal end of the base 21. The base surface 22a, the ramp surface 22b, the lift surface 22c, and the top surface 22d allow the swing cam 17 to swing. The upper surface 16a of each valve lifter 16 comes into contact with a predetermined position in accordance with the moving position.

That is, in view of the valve lift characteristics shown in FIG. 5, the predetermined angle range of the base circle surface 22a is the base circle section θ1 as shown in FIG. 2, and the predetermined angle range from the base circle section θ1 of the ramp surface 22b. The range is a so-called ramp section θ2, and the predetermined angle range from the ramp section θ2 of the ramp surface 22b to the top surface 22c is set to be a lift section θ3.

The transmission mechanism 18 includes a rocker arm 23 disposed above the drive shaft 13, a link arm 24 for linking one end 23a of the rocker arm 23 and the drive cam 15, and a second end 23b of the rocker arm 23. Swing cam 1
And a link rod 25 which is a link member for linking the link rod 7 with the link rod 7.

Each of the rocker arms 23 has a cylindrical base provided at the center of the rocker arm 23 through a support hole 23d.
It is supported rotatably. Further, a pin 2 is provided at one end 23a of each cylindrical base projecting from the outer end at the outer end.
6 is fitted through the pin hole, while the other end 23b projecting from each inner end of each base is fitted with a pin 27 connected to one end 25a of each link rod 25. Pin holes are formed.

The link arm 24 has an annular base 24a having a relatively large diameter and a protruding end 24b protruding at a predetermined position on the outer peripheral surface of the base 24a. A fitting hole 24c rotatably fitted to the outer peripheral surface of the cam body 15a of the driving cam 15 is formed, while a pin hole 24d through which the pin 26 is rotatably inserted penetrates the protruding end 24b. Is formed.

Further, as shown in FIG. 2, the link rod 25 is formed in a substantially rectangular shape in which the rocker arm 23 side is concave, and the other end 23b of the rocker arm 23 and the swing cam are provided at both ends 25a and 25b. 17 cam nose parts 2
Pin insertion holes 25c and 25d through which the ends of the pins 27 and 28 press-fitted into the respective pin holes 1 are rotatably inserted are formed to penetrate, and the axis of the pin 28 is at the pivot point of the swing cam 17 at the pivot point. Has become.

At one end of each of the pins 26, 27, and 28, snap rings 29, 30, and 31 for restricting the axial movement of the link arm 24 and the link rod 25 are provided.

The variable mechanism 19 includes a control shaft 32 rotatably supported by the same bearing 14 at a position above the drive shaft 13.
And the rocker arm 23 fixed to the outer periphery of the control shaft 32.
The rocker arm 2 is slidably fitted into the support hole 23d.
3 is provided with a control cam 33 serving as a swing support point.

The control shaft 32 is disposed in the engine front-rear direction in parallel with the drive shaft 13 as shown in FIG.
An electric actuator 34 provided at one end 32a rotates within a predetermined rotation angle range.

The control cam 33 has a cylindrical shape, and the position of the axis P1 is deviated by α from the axis P2 of the control shaft 32 by the thickness portion 33a as shown in FIG.

Further, an electric actuator 34 for controlling the rotation of the control shaft 32 within the rotation range of the above-mentioned minimum-maximum valve lift control is provided with a control signal from a controller 35 for detecting the operating state of the engine as shown in FIG. It is designed to be driven by. The controller 35 detects the current engine operation state based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a rotation position detection sensor 36 of the water temperature sensor control shaft 32 by calculation or the like. The control signal is output to the electromagnetic actuator 34.

As shown in FIGS. 1 and 3, the bias mechanism 40 is provided integrally with the other end 32b of the control shaft 32 in the axial direction, and protrudes outward from the outer end surface of the bearing 14. A projecting portion 41 and a rectangular boss portion 4 integrally provided on the outer end surface of the main bracket 14a of the bearing 14
2, a cylindrical cylinder 43 formed inside the boss portion 42 and having an open upper end side, and slidably provided inside the cylinder 43, and a tip end portion 44a is provided with the protruding portion 41a.
Cylindrical bracket 4 that is oriented substantially perpendicular to the axis
4 and a bias spring 45 elastically mounted in the cylinder 43 and biasing the plunger 44 toward the protruding portion 41.

As shown in FIGS. 1 to 3, the protruding portion 41 has a round bar shape having a circular cross section, and its axis P3 is positioned vertically upward at a predetermined distance β from the axis P2 of the control shaft 32. And a rectangular block-shaped sliding body 46 is provided on the outer periphery thereof. This sliding body 46
The protruding portion 41 is rotatably disposed in a through hole 46 a formed in the center along the axial direction of the control shaft 32, and the lower end surface 46 b is disposed on the upper surface of the distal end head 44 a of the plunger 44. It is slidably in contact. In addition, a snap ring 47 that regulates the sliding body 46 from dropping forward is provided at the tip of the protruding part 41.

In the following, the operation of the present embodiment will be described. First, when the engine is running at a low speed and low load, the control shaft 32 is driven to the rotational position shown in FIGS. You. For this reason,
The control cam 33 has its axis P1 (thick portion 33a) held at a rotation angle position on the left side from the axis P2 of the control shaft 32, as shown in FIG. As a result, the other end 23 of the rocker arm
b and the pivot point of the link rod move in the upper left direction with respect to the drive shaft 13, so that each swing cam 17 is forcibly pulled up on the cam nose portion 21 side via the link rod 25, and the whole swinging cam 17 is deflected. Rotate clockwise.

Accordingly, the drive cam 15 rotates and the one end 23a of the rocker arm 23 is rotated via the link arm 24.
Is lifted, the lift amount is transmitted to the swing cam 17 and the valve lifter 16 via the link rod 25, but the lift amount L1 becomes sufficiently small.

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

When the control shaft 32 is held at the above-described rotational position, the projecting portion 41 is positioned at the position shown by the one-dot chain line in FIGS. The control cam 33 is eccentrically rotated to a position substantially opposite to the axis P1. Therefore, the sliding body 46 is slid to the position shown by the one-dot chain line in FIG. For this reason, the plunger 44 and the sliding body 46
The spring force of the bias spring 45 acts vertically downward (diametrically) from below, and thus the control shaft 3
6A, the bias torque Fb against the resultant force Fc of F _R and Fa generated on the control shaft 32 due to the spring reaction force of the valve spring 10 as shown by the broken arrow in FIG. Occurs. That is, the bias torque Fb acts at a position substantially opposite to the resultant force Fc across the axis P2 of the control shaft 32 and substantially in parallel. Therefore, a clockwise rotational moment in the figure due to the resultant force Fc and a counterclockwise rotational moment in the figure due to the bias torque Fb act on the control shaft 32, and both torques Fc and Fb are generated. Since the two cancel each other out, the generation of the offset load torque (rotation moment) only in the clockwise direction due to the resultant force Fc can be suppressed.

Therefore, since the rotational load of the control shaft 32 in the direction in which the lift amount increases from the small valve lift region is reduced, control responsiveness can be improved. That is,
When the engine shifts from the low-speed low-speed range to the high-speed high-load state of the engine, the control shaft 32 is rotated counterclockwise in FIG. Accordingly, the control shaft 32 rotates the control cam 33 in the counterclockwise direction from the position shown in FIGS. 6A and 6B to move the axis P1 (thick portion 33a) downward as shown in FIGS. 7A and 7B. For this reason, the rocker arm 23 moves in the direction approaching the drive shaft 13 this time and the other end 23 b
Moves the cam nose portion 21 of the swing cam 17 to the link rod 25
To rotate the entire swing cam 17 clockwise by a predetermined amount.

Accordingly, the contact position of the cam surface 22 of the swing cam 17 with respect to the upper surface 16a of the valve lifter 16 moves rightward as shown in FIGS. 7A and 7B. For this reason, when the drive cam 15 rotates and pushes up one end 23a of the rocker arm 23 via the link arm 24 as shown in FIG. 7A when the intake valve 12 is opened, the lift amount L2 with respect to the valve lifter 16 is reduced as shown in FIG. It becomes larger as shown in FIG.

Accordingly, in such a high-speed and high-load region, the valve lift becomes large as shown by the solid line in FIG.
The opening timing of each intake valve 12 is advanced and the closing timing is delayed. As a result, the intake charging efficiency is improved, and a sufficient output can be secured.

As the control shaft 32 rotates in the direction of increasing the lift from the rotation position of the minimum valve lift control to the maximum valve lift control, the protrusion 41 also moves as shown in FIG.
7A and 7B by turning counterclockwise from the positions shown in FIGS.
1, that is, at the left side position in the figure near the axis P2 of the control shaft 32. With this rotation, the sliding body 46 also slides on the distal end head 44a of the plunger 44, as shown in FIG.
To the left two-dot chain line to continue applying the bias torque Fb. When the bias torque Fb of the bias torque mechanism 40 is viewed alone, FIG.
As shown in FIG. 3B, the maximum value is obtained during the small valve lift control, and approaches zero as the lift amount increases.
Since the rotation is reversed from the second axis P2, the torque slightly increases.

Therefore, the bias load torque acting on the control shaft 32 acts so that the bias torque Fb and the resultant force Fc cancel each other, as shown in FIG. 11C, so that it becomes minimum at the control position near the minimum valve lift, and the lift is reduced. As it gradually increases, it gradually increases due to a change in the relative position between the protrusion 41 and the control cam 33. However, at the maximum valve lift position, the straight line connecting the axis P2 of the control shaft 32 and the axis P1 of the control cam 33 is directed to the rocker arm 23.
Since the direction of the resultant force Fc matches the direction of the resultant force Fc, the offset load torque due to the resultant force Fc becomes zero as shown in FIG. 11A. Accordingly, the unbalanced load torque (clockwise rotation moment in the figure) acting on the control shaft 32 is only the bias torque Fb, and is sufficiently small.

As described above, the eccentric load torque acting on the control shaft 32 is suppressed to a small value from the minimum valve lift to the maximum valve lift control, and the positive and negative clockwise torques are changed to S1 and S2 in FIG. 11C. As shown, they can be set almost equal and small. As a result, the driving torque of the electric actuator 34 can be made sufficiently small, the electric actuator 34 can be made compact, and the mountability to the engine is improved.

The bias mechanism 40 is provided with
The lower end surface 46a of the sliding body 46 slides on the upper surface of the distal end head 44a of the plunger 44 with the forward / reverse rotation of 1 so that the protrusion 4
In order to follow the change in the rotation position, the spring force of the bias spring 45 can be constantly and reliably transmitted to the protrusion 41.

If the electric actuator 34 fails, for example, the plunger 44 of the bias mechanism 40 presses the protrusion 41 from below, and the position where the eccentric load torque Fc and the bias torque Fb are balanced (point B in FIG. 11C). ) Holds the control cam 33. Therefore, the control shaft 32 is always kept at the rotation neutral position, controls the valve lift to the intermediate lift position, and operates a so-called fail-safe function. Therefore, it is possible to prevent a large decrease in performance such as engine startability and fuel efficiency.

FIGS. 9 and 10 show a second embodiment of the present invention, in which the structure of the bias mechanism 40 is modified. That is, the projecting portion 41 integrally provided at the eccentric position of the other end portion 32a of the control shaft 32 is formed in a substantially elliptical cross section, and the lower surface 41a is formed in a curved shape. Further, the sliding body 46 is abolished, and the upper surface of the distal end head 44a of the plunger 44 abuts on the lower surface 41a of the projection 41. Other configurations are the same as in the first embodiment.

Therefore, according to this embodiment, the first
In the same manner as in the embodiment, the rotational driving torque of the control shaft 32 can be reduced, and when the protrusion 41 rotates with the rotation of the control shaft 32, the curved lower surface 41a of the protrusion 41 can be reduced.
Rolls smoothly on the upper surface of the distal end head 44a of the plunger 44 in a rolling manner.
The generation of a tapping noise with the upper surface 4a can be suppressed, and the occurrence of abrasion between the two can be prevented, so that the durability can be improved. Also,
By eliminating the sliding body 46, the number of parts can be reduced and the control work efficiency can be improved.

It should be noted that the present invention is not limited to the configuration of each of the above embodiments. For example, the lubricating oil is positively supplied to the bias mechanism 40 so that the plunger 44 and the sliding body 46 or the protruding portion 41 It is possible to improve the lubricating performance of the device, to obtain a smooth operation at all times, and to further prevent the occurrence of wear. In addition, the plunger 44 can be operated by hydraulic pressure instead of the bias spring.

[0050]

As is apparent from the above description, claim 1
According to the invention described above, since the bias mechanism can reduce the unbalanced load torque caused by the spring force of the valve spring on the control shaft, the drive torque of the actuator that rotationally drives the control shaft can be sufficiently reduced. As a result, control responsiveness can be improved and the size of the actuator can be reduced, and the mountability on the engine can be improved.

Further, when the actuator is out of order, the control shaft can be held at the middle rotation position by the bias mechanism, so that the fail-safe function is exhibited and the deterioration of the engine performance can be prevented.

According to the second aspect of the present invention, since the bias mechanism has a simple structure, the manufacturing workability is improved and the cost can be reduced.

According to the third aspect of the invention, smooth rotation of the protruding portion is obtained by sliding the block, and control responsiveness is further improved.

[Brief description of the drawings]

FIG. 1 is a view as viewed from an arrow A in FIG. 3, showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 3;

FIG. 3 is a plan view of a main part of the embodiment.

FIG. 4 is a perspective view of a driving cam provided in the embodiment.

FIG. 5 is a lift characteristic diagram of a cam surface of the swing cam provided in the embodiment.

6A is an operation explanatory view showing a valve closed state at the time of minimum valve lift control, and FIG. 6B is an operation explanatory view showing a valve open state.

FIG. 7A is an operation explanatory view showing a valve open state during maximum valve lift control. B is an operation explanatory view in a valve closed state.

FIG. 8 is a valve lift characteristic diagram of the present apparatus.

FIG. 9 is a sectional view of a bias mechanism provided in a second embodiment of the present invention.

FIG. 10 is an exemplary plan view of the bias mechanism provided in the embodiment;

11A is a characteristic diagram of an offset load torque generated on a control shaft having no bias mechanism, FIG. 11B is a characteristic diagram of a bias torque generated by the bias mechanism, and FIG. 11C is a characteristic diagram of a load torque generated on the control shaft due to the combined force of A and B. FIG.

FIG. 12 is a sectional view of a main part of a variable valve apparatus according to the prior application.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Valve spring 11 ... Cylinder head 12 ... Intake valve 13 ... Drive shaft 15 ... Drive cam 17 ... Swing cam 18 ... Transmission mechanism 19 ... Variable mechanism 23 ... Rocker arms 23a and 23b ... End part 32 ... Control shaft 33 ... Control cam Reference Signs List 40 bias mechanism 41 projecting part 42 boss part 43 cylinder 44 plunger 45 bias spring 46 sliding body (block) P1 axis of control cam P2 axis of control shaft

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shin Nakamura 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisex Jex Co., Ltd. (72) Inventor Yoshihiko Yamada 1370 Onna, Atsugi-shi, Kanagawa Prefecture Unicity Jex Co., Ltd. 72) Inventor Keisuke Takeda 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisex Jex Inc. (72) Inventor Tsutomu 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisex Jex Inc. (72) Inventor Tsuneyasu Nohara F-term (reference) in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa 3G016 AA06 AA19 BA03 BA23 BA37 CA13 CA25 CA27 CA28 CA29 CA43 CA47 CA48 CA57 GA00 GA01

Claims (3)

[Claims] 1. A drive shaft that rotates in synchronization with a crankshaft of an engine and has a drive cam provided on an outer periphery, a swing cam that opens an engine valve against a spring force of a valve spring, and one end. A rocker arm, the other end of which is linked to the swing cam, and a control shaft for swingably supporting the rocker arm via an eccentric control cam;
A variable valve apparatus for an internal combustion engine that controls a rotation position of the control shaft according to an engine operating state to change a rocking fulcrum position of a rocker arm to variably control a lift amount of an engine valve. And a biasing mechanism for applying a force opposing a one-way rotational force caused by an unbalanced load torque applied to a control shaft via a rocker arm and a control cam. 2. The bias mechanism is provided integrally with an end portion of the control shaft in an axial direction, and has a projection whose axis is eccentric from the axis of the control shaft, and is formed substantially in a direction perpendicular to the axis of the projection. A cylinder, a plunger slidably provided in the cylinder, and abutting on the protruding portion substantially in a direction perpendicular to the axis; The variable valve train for an internal combustion engine according to claim 1, further comprising a spring member for urging. 3. A block is rotatably provided on the projection, and a tip end of the plunger is elastically contacted with a lower end surface of the block via a spring member.
A variable valve train for an internal combustion engine according to claim 1.