JP2001263014A - Variable valve system for internal conbustuion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of collision hammering and collision between gears in speed reducing gear mechanism by an alternating torque generated caused by using force of a valve spring. SOLUTION: A rocker arm is slidably moved through a link arm by a driving cam fixed to a driving shaft 13, and an intake valve 112 is openingly operated against spring force of the valve spring 10 by a sliding cam 17 linked therewith. Ina bias mechanism 40, a plunger 44 is pushed up by spring force of a bias spring 45, a protrusion part 41 is push-pressingly energized, and thereby, a control shaft 32 is rotatingly energized in an anticlockwise direction at all times in the Figure. It is thus possible to suppress collision by the alternating torque by eliminating a backlash clearance between gears of the speed reducing gear mechanism.

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. 16, this variable valve device is applied to the intake valve side, and has a shaft center on the outer periphery of a drive shaft 51 which rotates in synchronization with the rotation of the 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.

The control shaft 57 is rotatably driven by an electric actuator (not shown) via a reduction gear mechanism. An outer peripheral surface of the control shaft 57 has a shaft center P1 at a predetermined angle α from the shaft center P2 of the control shaft 57. The control cam 64 which is only eccentric is fixed. The control cam 64 is rotatably fitted and held in a support hole 58c formed substantially at the center of the rocker arm 58, and changes the rocking fulcrum of the rocker arm 58 in accordance with the rotation position thereof. 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 the low rotation and low load range, as shown in FIG. 16, the electric actuator causes the control shaft 57 to rotate in the other direction via the reduction gear mechanism, thereby causing the control cam 64 to rotate. Is also rotated in the same direction, thereby moving the rocking fulcrum position of the rocker arm 58 in a direction away from the drive shaft 51. Thereby, the rocker arm 5
The pivot point between the rod 8 and the link rod 61 moves upward to raise the cam nose portion 56a of the swing cam 56, whereby the contact position of the swing cam 56 with respect to the upper surface of the valve lifter 54 moves away from the lift portion 55c. I do. Therefore, the intake valve 53 is controlled such that the valve lift is 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 range to the high rotation high load range, the control shaft 57 is moved by the electric actuator via the reduction gear mechanism in the direction of the broken arrow (counterclockwise).
To rotate the control cam 64 in the same direction,
As shown, the rocking fulcrum of the rocker arm 58 is
Move in the direction approaching 1. As a result, the swing cam 56
Since the end 56a is pushed down by the link rod 61 or the like, and the contact position on the upper surface of the valve lifter 54 moves to the lift portion 55c side, the valve lift of the intake valve 53 is controlled to be increased.

[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. Is variable, but the alternating torque caused by the spring force of the valve spring 65 is transmitted to the control shaft 57 via the transmission mechanism with the swing of the swing cam 56 due to the rotation of the drive cam 52, Collision hitting sound is likely to occur on each tooth side surface due to the backlash gap between each gear in the reduction gear mechanism.

[0010] That is, as shown in FIG. 16, 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, the rocker arm 58 by the F _S A pin 63, a link rod 61 and a pin 62
A force as an arrow F _R acts in a linear direction connecting the axes Z1 and Z3 of the pins 62 and 63 via the pin, while a pressing force due to the eccentric rotational force of the driving cam 52 is applied to one end 58a of the rocker arm 58. Through the link arm 59 and the pin 60, the force acts as a force indicated by an arrow Fa in the direction of a straight line (Q) connecting the axis X of the drive shaft 51 and the axis of the pin 60 (the pivot point Z2). Therefore, the resultant force (Fc) of F _R and Fa acts on the control cam 64. The F _C is the control shaft 57 axial center P2
Try to rotate clockwise. However, near the point where the lift is maximized, the directions of F _R , Fa and Fc are reversed due to the negative inertia acting on the rocker arm 58 and the control cam 64. At this time, the control shaft 57 is set to P by Fc.
Try to turn counterclockwise two turns. Therefore, the resultant force F _C acts as a clockwise or counterclockwise alternating torque during one rotation of the drive shaft 51, that is, an alternating torque for rotating the control cam 64 clockwise or counterclockwise in the drawing. Therefore, an alternating torque is generated in the control shaft 57 in the clockwise direction or the counterclockwise direction.

The magnitude of the alternating torque changes according to the change in the rotational position of the control shaft 57 and the valve lift.
For example, FIG. 12A shows a change in torque when one of the counterclockwise torques is positive in the alternating torque. According to this figure, a relatively large alternation torque variation is transmitted to the control shaft 57 from the rotation position of the small valve lift control to the maximum valve lift. As a result, due to the alternating torque, the gap existing in the link between the control shaft 57 and the actuator (not shown), that is, the gears of, for example, the reduction gear mechanism between them have relatively large collisions due to the backlash of the tooth side surfaces colliding with each other. There is a possibility that a tapping sound is generated.

[0012]

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 Is linked to the drive cam while the other end is linked to the swing cam, a rocker arm that swingably supports the rocker arm via an eccentric control cam, and an actuator that rotates the control shaft. A variable valve apparatus for an internal combustion engine that variably controls a lift amount of an engine valve by controlling a rotational position of the control shaft according to an engine operating state to change a rocking fulcrum position of a rocker arm. The shaft is provided with a bias mechanism for applying a rotational urging force in one direction regardless of the rotational phase of the control shaft.

Therefore, according to the present invention, the control shaft is always urged to rotate in one direction by the bias mechanism, whereby rattling noise due to backlash between the gears of the reduction gear mechanism due to the alternating torque is suppressed. You.

According to a second aspect of the present invention, the bias mechanism extends in the axial direction at the end of the control shaft, and the center of the bias is shifted leftward or rightward about a diameter line passing through the axis of the control shaft. And a biasing means for biasing the protrusion from a direction substantially perpendicular to the axis to apply a rotational biasing force in one direction to the control shaft.

According to a third aspect of the present invention, the urging means includes:
A cylinder formed substantially perpendicular to the axis of the projection, and a plunger slidably provided in the cylinder and abutting the projection substantially perpendicular to the axis;
A spring member for pressing the protruding portion via the plunger.

According to a fourth aspect of the present invention, the urging means comprises:
It is characterized by being driven by a pump whose discharge rate increases with an increase in the engine speed.

According to a fifth aspect of the present invention, there is provided a drive shaft which rotates in synchronization with a crankshaft of an engine and has a drive cam provided on an outer periphery thereof, and a swing shaft for opening an engine valve against a spring force of a valve spring. A rocker arm having one end linked to the drive cam and the other end linked to the swing cam;
A control shaft for swingably supporting the rocker arm via a control cam; and an actuator for rotating the control shaft. The rocker arm swings by controlling the rotational position of the control shaft in accordance with an engine operating state. In a variable valve operating apparatus for an internal combustion engine that variably controls a lift amount of an engine valve by changing a fulcrum position, an oil groove is formed on an inner peripheral surface of the drive shaft side of a support hole of a rocker arm inserted and supported by the control cam. It is characterized by:

According to a sixth aspect of the present invention, a portion of the rocker arm on the side of the drive shaft, in which a support hole through which the control cam is inserted and supported, is formed with high rigidity.

According to a seventh aspect of the present invention, between the outer peripheral surface of the control cam and the inner peripheral surface of the support hole of the rocker arm inserted and supported by the control cam, and the rocker arm is connected via the outer peripheral surface of the control cam. It is characterized in that lubricating oil is supplied to a position on the side that swings in the valve lift direction.

According to an eighth aspect of the present invention, the coefficient of friction between the control cam and the support hole of the rocker arm inserted and supported by the control cam is made smaller than the coefficient of friction between the control shaft and the bearing. It is characterized by.

According to a ninth aspect of the present invention, a low friction material is formed on the outer peripheral surface of the control cam, and the friction coefficient between the control cam and the support hole of the rocker arm is determined by the friction between the control shaft and the bearing. It is characterized by being smaller than the coefficient.

[0022]

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 4, the 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 or 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. 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. 5, 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 closed cylindrical shape, 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 21 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, from the viewpoint of the valve lift characteristics shown in FIG. 6, the predetermined angle range of the base circle surface 22a becomes the base circle section θ1 as shown in FIG. 3, 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.

As shown in FIG. 3, each rocker arm 23 has a central cylindrical base 23c rotatably supported by a control cam 33 described later via a support hole 23d. Further, a pin hole into which the pin 26 is inserted is formed through the one end 23a protruding from the outer end of each cylindrical base 23c at the outer end, while the inner end of each base is formed at the inner end of each base. Each of the projecting other end portions 23b has a pin hole into which a pin 27 connected to one end portion 25a of each link rod 25 is fitted.

The link arm 24 has a relatively large-diameter annular base 24a and a protruding end 24b projecting from 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. 3, the link rod 25 is formed in a substantially rectangular shape in which the rocker arm 23 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, 28, snap rings 29, 30, 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, a control cam 33 serving as a swing fulcrum, an electric actuator 34 for controlling the rotational position of the control shaft 32 via a reduction gear mechanism 38, and a controller for controlling the drive of the electric actuator 34 according to the engine operating state. 35.

The control shaft 32 is disposed in the engine front-rear direction in parallel with the drive shaft 13 as shown in FIG.
The rotation is controlled within the rotation range of the minimum-maximum valve lift control by the electric actuator 34 via the reduction gear mechanism 38 provided on the one end 32a side.

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

The reduction gear mechanism 38 is fixed to the small diameter first spur gear 38a fixed to the drive rod 34a of the electric actuator 34, and is fixed to one end 32a of the control shaft 32 to mesh with the first spur gear 38a. Large diameter second spur gear 3
8b.

The electric actuator 34 employs a step motor, and is driven to rotate forward and backward by a control signal from the controller 35. The controller 35 includes a crank angle sensor, an air flow meter, a water temperature sensor, and a rotation position detection sensor 3 for the control shaft 32.
Based on detection signals from various sensors such as 6 and the like, the current engine operating state is detected by calculation or the like, and a control signal is output to the electromagnetic actuator 34.

The bias mechanism 40 is shown in FIGS.
As shown in FIGS. 2 and 4, the other end 32b of the control shaft 32
The projection 41 is integrally extended from the axial direction, and protrudes outward from the outer end face of the bearing 14. The urging means presses and urges the projection 41 substantially at right angles to the axis. .

As shown in FIGS. 1, 2, and 4, the projecting portion 41 has a round bar shape having a circular cross section, and has an axis P3.
(Vertical line E) is deviated to the right in FIG. 1 from a vertical diameter line H passing through the axis P2 of the control shaft 32.

The urging means includes a rectangular boss portion 42 integrally provided on the outer end surface of the main bracket 14 a of the bearing 14, and an upper end formed in the boss portion 42 and having an upper end directed toward the protruding portion 41. A cylindrical cylinder 4 opened from below
3 and slidably provided inside the cylinder 43,
A cylindrical plunger 44 with a closed end whose head 44a is oriented substantially perpendicular to the axis of the projection 41; a bias spring 45 elastically mounted in the cylinder 43 to bias the plunger 44 toward the projection 41; It is composed of

In the following, the operation of this embodiment will be described. First, when the engine is running at a low speed and a 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 moved through 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 broken line in FIG. . 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 moves to the position shown by the one-dot chain line in FIGS. It eccentrically rotates to a lower position. Therefore, the protrusion 41
, The spring force of the bias spring 45 acts vertically downward (diametrically) from below through the plunger 44 and the sliding body 46, whereby the control shaft 32
1 and 7A, a rotational urging force in the counterclockwise direction, that is, a bias torque is applied. As a result, the second spur gear 38b is also urged to rotate to one side as shown by the arrow in FIG. 4, and each tooth side elastically contacts each opposing tooth side of the first spur gear 38a to eliminate the backlash gap. .

On the other hand, when the engine shifts from the low-speed low-speed range to the high-speed engine high-load condition, the control shaft 32 is rotated by the electric actuator 34 by the control signal from the controller 35, and the control cam 33 is moved from the position shown in FIGS. 8A and 8B, the shaft center P1 (thick portion 33a) is rotated counterclockwise.
Is turned downward as shown in FIG. For this reason, rocker arm 2
3 is moved in the direction approaching the drive shaft 13 and the other end 23b presses the cam nose portion 21 of the swing cam 17 downward via the link rod 25, thereby causing the swing cam 17 to move downward.
The whole is rotated 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 to the right position as shown in FIGS. 8A and 8B. 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. 8A when the intake valve 12 is opened, the lift amount L2 with respect to the valve lifter 16 becomes It becomes larger as shown in FIG.

Therefore, 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 (rotation in the counterclockwise direction), the protrusion 41 is also shown in FIGS. 7A and 7B. 2 and 8A and 8B, that is, a position above the control shaft 32. Accordingly, the head 44a of the distal end of the plunger 44 moves the projecting portion 41 in FIG.
As shown by the dashed arrow, the pressure continues to be urged in the counterclockwise direction as in FIG.

When the bias torque Fb of the bias torque mechanism 40 is viewed alone, the bias torque Fb of FIG.
As shown in FIG. 1, a substantially constant torque is generated from the small valve lift control to the large lift control.

On the other hand, the alternating torque acting on the control shaft 32 is, as shown by G1 in FIG.
And the minimum torque (MIN) shown in FIG. 12A to which the bias torque is not applied acts so as to cancel each other, so that the overall torque becomes smaller.

As described above, the alternating 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 control shaft 32 is constantly turned counterclockwise by the bias torque as described above. The second spur gear 38 of the reduction gear mechanism 38
b is rotationally urged in the same direction, and the respective tooth side surfaces of the second spur gear 38b are always in elastic contact with the opposing tooth side surfaces of the first spur gear 38a with a predetermined torque. Therefore, the two spur gears 38
The backlash gap between a and 38b disappears. Therefore, collision of the spur gears 38a and 38b due to the alternating torque transmitted to the control shaft 32 is avoided, and the occurrence of the collision sound can be reliably suppressed.

FIGS. 10 and 11 show a second embodiment of the present invention, in which the biasing means of the bias mechanism 40 is almost the same, but the structure of the projecting portion is changed to a cam type. That is, the cam-shaped projection 46 provided integrally with the other end 32b of the control shaft 32 has a substantially raindrop shape as a whole, and the base 46a forming the base circle is integrally fixed to the front end edge of the control shaft 32. The center P3 of the base 46a.
The (vertical line E) is slightly deviated rightward from the axis P2 (vertical line H) of the control shaft 32 as shown in the drawing. In addition, the base 4
A distal end 46b extending in the radial direction of the control shaft 32 from 6a extends more than the outer diameter of the control shaft 32, and curved cam surfaces 47a, 47b are formed on both sides.

On the other hand, the urging means has the same basic structure of the boss 42, the cylinder 43, the plunger 44 and the bias spring 45 as in the first embodiment. The projection 46 is always in elastic contact with the one-side cam surface 47a of the projection 46 by a spring force to urge the projection 46 to rotate counterclockwise in the drawing.

The bias torque is applied to the protrusion 4
12B is formed in an elongated cam shape, and when viewed alone, as shown by V2 in FIG. 12B, a ramp region is formed from the base circle of the cam surface 47a from the minimum to the middle lift region. However, a large bias torque occurs in the maximum lift region. Therefore, when the bias torque by the protrusion 46 is applied to the control shaft 32, the minimum alternating torque (MIN) is suppressed, and the combined torque is smaller than that of the first embodiment as shown by G2 in FIG. 12C. Effectively reduced. As a result,
The drive load of the electric actuator 34 can be reduced.

Further, since the backlash gap between the two spur gears 38a and 38b can be eliminated via the control shaft 32 by the bias torque, the occurrence of collision between the tooth side surfaces can be suppressed.

Hereinafter, embodiments corresponding to the fifth to ninth aspects will be described. In each of the embodiments, the control cam 33 and the support holes 23d are mainly provided without the above-mentioned bias mechanism.
The transmission of the alternating torque is suppressed by reducing the friction between them.

FIG. 13 shows an embodiment corresponding to claim 5, in which an oil groove 50 is formed in the inner peripheral surface of the support hole 23d formed through the inside of the cylindrical base 23c of the rocker arm 23. That is, the oil groove 50 is formed in the support hole 23d.
An arc-shaped notch is formed in the inner peripheral surface on the drive shaft 13 side. In the oil groove 50, lubricating oil is supplied from an oil passage 51 formed in the inner axial direction of the control shaft 32 and an oil hole 52 formed continuously in the diameter direction of the control shaft 32 and the control cam 33. It is being supplied.

Therefore, according to this embodiment, an oil film is always formed between the inner peripheral surface of the support hole 23 of the rocker arm 23 and the outer peripheral surface of the control cam 33 by the lubricating oil supplied into the oil groove 50. The fluid lubrication state can be provided between the two 23 and 33. For this reason, it is possible to greatly reduce the friction between the two 23 and 33, and to control the aforementioned alternating torque control cam 33 transmitted to the rocker arm 23.
, That is, rotation of the control cam 33 due to rocking of the rocker arm 23 is prevented.

As a result, the reduction gear mechanism 3
8, the transmission of the alternating torque to the teeth 38a, 3
It is possible to prevent occurrence of a tapping sound during the period 8b and reduce the driving load on the control shaft 32.

In particular, since the oil groove 50 is formed on the drive shaft 13 side of the inner peripheral surface of the support hole 23d, the spring reaction force of the valve spring 10 acts on the control cam 33 from the rocker arm 23 during the maximum lift control shown in FIG. Rocker arm 23
It is possible to effectively reduce the friction between the two 23 and 33 when the valve lift rises due to the swing of the valve.

FIG. 14 shows an embodiment corresponding to the sixth aspect of the present invention, in which a support hole 23d of the rocker arm 23 is provided.
The portion 23e of the base 23c on which the drive shaft 13 is formed is formed thick to increase the rigidity of the portion 23e.

Therefore, for example, when shifting from the minimum lift to the maximum lift control, both ends 23a, b (Z1, Z2) of the rocker arm 23 accompanying the swing in the valve lift ascending direction.
Input load Fa acting on the Z2), F _R and a control cam 3
The base 23c which is easily generated by the reaction force (large arrow) of No. 3
The deformation of the portion 23e of the (supporting hole 23d) on the drive shaft 13 side is suppressed. As a result, an increase in friction due to partial pressure contact between the outer peripheral surface of the control cam 33 and the inner peripheral surface of the support hole 23d due to the deformation of the support hole 23d is suppressed, and the movement of the rocker arm 23 to the control cam 33 and the control shaft 32 is suppressed. Transmission of the alternating torque can be suppressed.

FIG. 15 shows an embodiment corresponding to claim 7, in which lubricating oil is supplied to a predetermined portion 60 between the outer peripheral surface of the control cam 33 and the inner peripheral surface of the support hole 23d. . That is, the predetermined portion 60 is a position on the side where the rocker arm 23 swings in the valve lift direction via the outer peripheral surface of the control cam 33 as shown in FIG.
0 is lubricated by an oil passage 61 formed in the inner axial direction of the control shaft 32 and an oil hole 62 formed substantially in the radial direction of the control shaft 32 and the control cam 33 as in the fifth embodiment. Oil is always supplied.

Therefore, according to this embodiment, when the rocker arm 23 swings in the valve lift ascending direction (in the direction of the arrow), for example, during the period from the minimum lift control position to the maximum lift control due to the rotation of the control shaft 32, the control is performed. The large pressing load position between the outer peripheral surface of the cam 33 and the inner peripheral surface of the support hole 23d shifts from the upper end side to the lower end side of the predetermined portion 60. At this time, the outer open end 62a of the oil hole 62 is sequentially It moves from the upper end side to the lower end side, and always positively supplies the lubricating oil to the predetermined portion 60 side. Therefore, both 23
An oil film is formed between d and 33, and lubricity is improved. As a result, the rotation of the control shaft 32 accompanying the rocking of the rocker arm 23 is prevented, and the transmission of the alternating torque from the rocker arm 23 is suppressed.

Further, as an embodiment corresponding to claim 8, a friction coefficient (surface roughness) between the inner peripheral surface of the support hole 23d of the rocker arm 23 and the outer peripheral surface of the control cam 33 slidingly contacting the inner peripheral surface is set. ) Is set smaller than the friction coefficient (surface roughness) between the inner peripheral surface of the bearing hole of the bearing 14 that supports the control shaft 32 and the outer peripheral surface of the control shaft 32.

As described above, a predetermined coefficient of friction is generated between the inner peripheral surface of the support hole 23d and the outer peripheral surface of the control cam 32.
Of course, friction occurs between the bearing 2 and the bearing 14 that rotatably supports the bearing 2. Therefore, friction between the support hole 23d and the control cam 33 is reduced.
By setting the friction between the two members 14 and 32 to be smaller, the rotation of the control cam 33 due to the swing of the rocker arm 23 is suppressed, and the behavior of the control shaft 32 is destabilized by the friction on the bearing 14 side. Can be suppressed. As a result, it is possible to prevent the generation of a tapping sound of the reduction gear mechanism 38.

Further, as a corresponding embodiment of the ninth aspect, a low friction material such as a fluoro resin is formed on the outer peripheral surface of the control cam 33 so that a space between the control shaft 32 and the bearing 14 is formed. It was set smaller than the coefficient of friction. Therefore, the same function and effect as the eighth aspect of the invention can be obtained.

The present invention is not limited to the configuration of each of the above embodiments. For example, the shape of the protruding portion of the bias mechanism 40 can be variously changed, and the urging means can be provided in each of the embodiments. It is not limited to the configuration.

[0071]

As is apparent from the above description, claim 1
According to the invention described above, since the control shaft is constantly biased to rotate in one direction by the bias mechanism, the alternating torque generated in the control shaft can be reduced, and the occurrence of collision between the gears due to the alternating torque is reliably suppressed. And as a result,
The generation of the impact sound and the wear between the tooth side surfaces due to the collision can be prevented.

According to the second and third aspects 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 fourth aspect of the present invention, the pump speed increases as the engine speed increases, and the urging means is pressed with a higher pressure. It is possible to effectively bias the torque.

According to the fifth aspect of the present invention, an oil film is always formed between the inner peripheral surface of the rocker arm support hole and the outer peripheral surface of the control cam by the lubricating oil supplied into the oil groove, and a fluid is formed between the two. Can be lubricated. For this reason, the friction between the two can be greatly reduced, and the transmission of the aforementioned alternating torque transmitted to the rocker arm to the control cam, that is, the control cam 33 caused by rocking of the rocker arm.
Is prevented.

As a result, the transmission of the alternating torque from the control shaft to the reduction gear mechanism is suppressed, and it is possible to prevent the occurrence of a tapping noise between the teeth and to reduce the driving load on the control shaft.

According to the sixth aspect of the present invention, an input load acting on the rocker arm due to the swing in the valve lift ascending direction and a reaction force of the control cam with respect to the input load, the support hole on the drive shaft side of the support hole which is likely to be generated. Deformation of the part is suppressed. As a result, an increase in friction due to partial pressure contact between the outer peripheral surface of the control cam and the inner peripheral surface of the support hole due to deformation of the support hole is suppressed, and transmission of alternating torque from the rocker arm to the control shaft can be suppressed.

According to the seventh aspect of the present invention, when the rocker arm swings in the valve lift ascending direction during the period from the minimum lift control position to the maximum lift control, the outer peripheral surface of the control cam and the inner peripheral surface of the support hole become large. The pressure contact load position shifts from the upper end side to the lower end side of the predetermined portion. At this time, the oil hole sequentially moves from the upper end side to the lower end side of the predetermined portion to always supply the lubricating oil to the predetermined portion side positively. Therefore, an oil film is formed between the two, and lubricity is improved. As a result, the rotation of the control shaft accompanying the rocking of the rocker arm is prevented, and the transmission of the alternating torque from the rocker arm is suppressed. According to the eighth and ninth aspects of the invention, the friction between the support hole and the control cam is set smaller than the friction between the control shaft and the bearing by providing a low friction material or the like between the two. In addition to suppressing the rotation of the control cam caused by the swing of the shaft, the behavior of the control shaft can be suppressed from becoming unstable due to friction on the bearing side.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a first embodiment of a variable valve apparatus according to the present invention, as viewed in the direction of arrow A in FIG. 4;

FIG. 2 is a view taken in the direction of arrow A in FIG. 4 showing the operation of the embodiment.

FIG. 3 is a sectional view taken along line BB of FIG. 4 of the embodiment;

FIG. 4 is a side view of a main part of the embodiment.

FIG. 5 is a perspective view of a drive cam provided in the embodiment.

FIG. 6 is a lift characteristic diagram of a cam surface of the swing cam provided in the embodiment.

FIG. 7A is an operation explanatory view showing a valve closing state at the time of minimum valve lift control, and FIG. 7B is an operation explanatory view showing a valve opening state.

FIG. 8A 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. 9 is a valve lift characteristic diagram of the present apparatus.

FIG. 10 is a front view of a bias mechanism provided in the second embodiment.

FIG. 11 is a diagram illustrating the operation of the bias mechanism.

12A is a characteristic diagram of an uneven load torque generated on a control shaft having no bias mechanism, FIG. 12B is a characteristic diagram of a bias torque generated by the bias mechanism, and FIG. 12C is a characteristic of a load torque generated on the control shaft due to the combined force of A and B. FIG.

FIG. 13 is a schematic view showing a main part of an embodiment according to claim 5;

FIG. 14 is a schematic view showing a main part of an embodiment according to claim 6;

FIG. 15 is a schematic view showing a main part of an embodiment according to claim 7;

FIG. 16 is a sectional view of a main part of a variable valve apparatus according to the prior application.

[Description of Signs] 10 ... valve spring 11 ... cylinder head 12 ... intake valve 13 ... drive shaft 15 ... drive cam 17 ... oscillating cam 18 ... transmission mechanism 19 ... variable mechanism 23 ... rocker arm 23a, 23b ... end 32 ... control Shaft 33 ... Control cam 38 ... Reduction gear mechanism 40 ... Bias mechanism 41/46 ... Protrusion 42 ... Boss 43 ... Cylinder 44 ... Plunger 45 ... Bias spring P1 ... Control cam axis P2 ... Control axis P3 ... Projection axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsuneyasu Nohara 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. F-term (reference) 3G013 AA05 BC12 BC16 BD35 3G018 AB03 AB16 BA19 BA32 CA07 CA13 DA03 DA12 DA19 DA23 EA22 EA31 FA01 FA06 GA22 GA27 3G092 AA11 DA05 DA12 DG05 FA02 FA13 FA14 GA03 GA16

Claims (9)

[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. Is linked to the drive cam while the other end is linked to the swing cam, a rocker arm that swingably supports the rocker arm via an eccentric control cam, and an actuator that rotates the control shaft. A variable valve apparatus for an internal combustion engine that variably controls a lift amount of an engine valve by controlling a rotational position of the control shaft according to an engine operating state to change a swing fulcrum position of a rocker arm. A variable valve train for an internal combustion engine, comprising: a shaft provided with a bias mechanism for applying a rotational urging force in any one direction regardless of the rotational phase of the control shaft. 2. The control device according to claim 1, wherein the biasing mechanism extends in an axial direction of an end of the control shaft, and has a protrusion whose axis is deviated from the axis of the control shaft, and attaches the protrusion from a direction substantially perpendicular to the axis. 2. A variable valve operating device for an internal combustion engine according to claim 1, further comprising: urging means for urging the control shaft to apply a rotational urging force in one direction to the control shaft. 3. The urging means includes a cylinder formed substantially perpendicular to the axis of the projecting portion and a slidably provided cylinder. 3. The variable valve train for an internal combustion engine according to claim 2, further comprising: a plunger that abuts from a direction, and a spring member that presses the protrusion through the plunger. 4. A variable valve operating apparatus for an internal combustion engine according to claim 2, wherein said urging means is driven by a pump whose discharge amount increases as the engine speed increases. 5. A drive shaft which rotates in synchronization with a crankshaft of the engine and has a drive cam provided on an outer periphery, a swing cam for opening an engine valve against a spring force of a valve spring, and one end portion. Is linked to the drive cam while the other end is linked to the swing cam, a rocker arm that swingably supports the rocker arm via an eccentric control cam, and an actuator that rotates the control shaft. A variable valve apparatus for an internal combustion engine that variably controls a lift amount of an engine valve by controlling a rotational position of the control shaft according to an engine operating state to change a swing fulcrum position of a rocker arm. A variable valve gear for an internal combustion engine, wherein an oil groove is formed in an inner peripheral surface of the support shaft side of the rocker arm through which the cam is inserted and supported on the drive shaft side. 6. A drive shaft that rotates in synchronization with a crankshaft of the engine and has a drive cam provided on the outer periphery, a swing cam that opens the engine valve against a spring force of a valve spring, and one end portion. A rocker arm having the other end linked to the swing cam, a control shaft for swingably supporting the rocker arm via the control cam, and an actuator for rotating the control shaft. A variable valve device for an internal combustion engine that variably controls a lift amount of an engine valve by controlling a rotation position of the control shaft according to an engine operating state to change a swing fulcrum position of a rocker arm. A variable valve gear for an internal combustion engine, wherein a portion on the drive shaft side where a support hole through which the control cam is inserted and supported is formed is formed with high rigidity. 7. A drive shaft rotating in synchronization with a crankshaft of the engine and having a drive cam provided on an outer periphery thereof, a swing cam for opening an engine valve against a spring force of a valve spring, and one end portion. A rocker arm having the other end linked to the swing cam, a control shaft for swingably supporting the rocker arm via the control cam, and an actuator for rotating the control shaft. A variable valve gear for an internal combustion engine that variably controls a lift amount of an engine valve by controlling a rotational position of the control shaft in accordance with an engine operating state to change a rocking fulcrum position of a rocker arm. Between the outer peripheral surface of the locker arm and the inner peripheral surface of the support hole of the rocker arm inserted and supported by the control cam, and on the side where the rocker arm swings in the valve lift direction via the outer peripheral surface of the control cam. oil Variable valve device for an internal combustion engine, characterized in that the supplied. 8. A drive shaft that rotates in synchronization with a 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 a valve spring, and one end. Is linked to the drive cam, while the other end is rotatably supported on a cylinder head via a bearing and a rocker arm linked to the swing cam, and the rocker arm is swingably supported via a control cam. Control shaft, and an actuator for rotationally driving the control shaft. The lift position of the engine valve is varied by controlling the rotational position of the control shaft in accordance with the engine operating state to change the rocking fulcrum position of the rocker arm. In the variable valve device for an internal combustion engine to be controlled, a coefficient of friction between the control cam and a support hole of the rocker arm inserted and supported by the control cam is smaller than a coefficient of friction between the control shaft and a bearing. Variable valve device for an internal combustion engine, characterized in that the. 9. A low friction material is formed on an outer peripheral surface of the control cam so that a friction coefficient between the control cam and the rocker arm support hole is smaller than a friction coefficient between the control shaft and a bearing. The variable valve train for an internal combustion engine according to claim 8, wherein