JP2000213314A - Variable valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the torque fluctuation of a control shaft with the direction of pressing force, transmitted from a drive cam to a link arm one end part, fixed, by sharply reducing frictional resistance between the drive cam and the link arm one end part. SOLUTION: This system is equipped with a drive shaft provided with a drive cam 15 on the outer periphery, and an oscillation cam 17 oscillation-freely supported by the drive shaft and for openingly/closingly actuating a suction valve 12 via a valve lifter 16. The rotating force of the cam 15 is transmitted to the cam 17 via a link arm 24, a rocker arm 23, and a link rod 25, and also a control cam 33 on the outer periphery of a control shaft 32 is rotatively controlled, to change the oscillation fulcrum of the rocker arm to make a valve lift variable. A needle bearing 43 is interposed between the outer peripheral surface of a cam main body and the inner peripheral surface 24c of a link arm base part 24a, to reduce the frictional resistance between both surfaces.

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 device for an internal combustion engine which can vary, for example, an intake valve or an exhaust valve, in particular, a valve lift according to an engine operating state.

[0002]

2. Description of the Related Art Conventional variable valve gears of this type include:
Referring to FIG. 12 showing a similar structure described in Japanese Patent Application No. 9-212831 filed earlier by the present applicant, this variable valve apparatus is applied to the intake valve side. A drive cam 52 whose axis Y is eccentric from the axis X of the drive shaft 51 is provided on the outer periphery of the drive shaft 51 that rotates in synchronization with the rotation of the crankshaft. Rotational force is transmitted through a multi-link transmission mechanism, and a cam surface 55 slidably contacts an upper surface of a valve lifter 54 provided at an upper end portion of the intake valve 53, thereby causing a swing cam 56 that opens and closes the intake valve 53 to operate. Have.

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 base end portion 59a fitted on an outer peripheral surface 52a of a drive cam 52. And the other end 59b is the rocker arm 58.
A link arm 59 rotatably connected via a pin 60 to one end 58a of the lock arm 5a.
8 is rotatably connected to the other end 58b of the swing cam 56 via a pin 62.
And a link rod 61 which is rotatably connected via a link.

A control cam 64 whose axis P1 is eccentric from the axis P2 of the control shaft 57 by a predetermined amount is fixed to the outer peripheral surface of the control shaft 57. 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 respect to the upper surface of the valve lifter 54, the valve lift of the intake valve 53 is variably controlled.

That is, when the engine operating state is, for example, in a low rotation and low load range, the control shaft 57 is rotated, for example, clockwise in the figure by an actuator (not shown), and the control cam 64 is rotated in the same direction. , Rocker arm 5
8 is moved to the left from the position shown in the figure.
As a result, the pivot points of the rocker arm 58, the link arm 59, and the link rod 61 move to the left to raise the end of the swing cam 56 on the cam nose portion 56a side. The upper contact position moves toward the base portion 55a. Therefore, the intake valve 53 is controlled such that its valve lift characteristic becomes a small lift.

On the other hand, when shifting to a high rotation and high load region,
Since the actuator controls the rotation of the control cam 64 to the illustrated position via the control shaft 57, the swing fulcrum of the rocker arm 58 moves in the opposite direction. 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 with the upper surface of the valve lifter 54 moves to the lift top surface 55d side, the valve lift of the intake valve 53 is controlled to be a large lift. You.

Therefore, engine performance such as improvement of fuel efficiency and output can be sufficiently exhibited in accordance with the operating state of the engine.

[0008]

However, in the above-described conventional variable valve operating device, the swinging fulcrum of the rocker arm 58 is changed in accordance with the rotational position of the control cam 64, so that the valve lift characteristic can be varied in size. However, no consideration is given to the rotation control of the control cam 64, that is, the stabilization of the torque acting on the control shaft 57 during the rotation of the control shaft 57.

That is, during the opening operation of the intake valve 13, the spring force of a valve spring (not shown) acts as Fs on the swing cam 56 via the valve lifter 54, and thereby the moment M in the direction of the arrow in FIG. ₁ is added. The link rod 61 by the M _1, the link rod end portions 61a,
Reaction force F _{1 in the} direction connecting the axes of both pins 62 and 63 of 61b.
Acts on the pin 63, and the F ₁ acts on one end of the rocker arm 58 via the pin 62. The rocker arm 58 receives a counterclockwise moment at the center of the swing fulcrum due to this F ₁ , but F ₂ ′ acts on the other end of the rocker arm 58 via the pin 60, and balances this moment. Will be.

Next, considering the direction of F ₂ ′, a relatively large sliding friction coefficient μ exists between the outer peripheral surface 52 a of the driving cam 52 and the inner peripheral surface 59 c of the one end 59 a of the link arm 59. Because of this friction coefficient, the drive cam 52 presses the pressing point between the outer peripheral surface 52a of the drive cam 52 and the inner peripheral surface 59c of the link arm 59, for example, as shown in FIG.
If it is rotating in the direction of the arrow 2 (counterclockwise),
It is located at point P, which is opposite to the rotation direction and deviates from the straight line Q connecting the center Y of the drive cam 52 and the center 60a of the pin 60. The pressing force from the driving cam 52 is divided into a normal force N and a frictional force μN from the point P, and becomes a force F ₂ ′ in the direction of a straight line Q 1 connecting the point P and the axis 60 a of the pin 60, and the link arm 59. This F ₂ ′ acts on the other end of the rocker arm via the pin 60. Here, assuming that μ is 0, the direction of F ₂ ′ becomes the straight line Q direction and is indicated by FX,
Due to the presence of μ, the direction of F ₂ ′ is shifted from the straight line Q by an angle of △ θ to become the Q1 direction.

For this reason, the reaction force F of the control cam 64 receiving both the reaction forces F ₁ and F ₂ ′ acting on the pins 62 and 60.
The direction of c ′ changes from Fcx toward the F ₂ ′ side, and the direction of the force acting on the axis P2 of the control shaft 57 from the control cam 64 is shifted from Q ₂ by △ ψ. As a result, the moment arm with respect to the center P ₂ of the control shaft 57 is also increased by △ t min, the torque fluctuation of the control shaft 57 is liable to occur thereby.

In particular, when starting the engine, the outer peripheral surface 52a of the drive cam 52 and one end 59a of the link arm 59 are connected.
When a sufficient amount of lubricating oil is not supplied to the inner peripheral surface 59c, or when the temperature of the lubricating oil is excessively increased, the lubricating performance between the two 52a and 59c is reduced, and the friction coefficient μ tends to vary. Therefore, the inclination angle of the straight line Q1 is easily changed. As a result, the torque characteristics of the control shaft 57 greatly vary between the solid line and the broken line in FIG. 12, and the response characteristics of an actuator such as a motor for rotating the control shaft 57 vary, and the rotational position control of the control cam 64 is performed. Becomes unstable. For this reason, valve lift control according to the engine operating state becomes unstable, and there is a possibility that engine performance cannot be effectively exhibited.

[0013]

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation of the variable valve operating device according to the prior application, and the invention according to claim 1 synchronizes with a crankshaft of an engine. A drive shaft that rotates and has a drive cam provided on the outer periphery, a swing cam that is swingably supported by a predetermined support shaft to open and close the engine valve, and an annular end slides on the outer periphery of the drive cam. A link arm movably fitted and a control shaft disposed substantially parallel to the drive shaft are swingably provided, and one end is rotatably linked to the other end of the link arm. A rocker arm associated with the rocking cam, a control cam having an axial center fixed to the outer periphery of the control shaft in an eccentric state, and changing a rocking fulcrum of the rocker arm according to a rotational position of the control shaft, The engine valve on the cam surface of the swing cam according to the change of the swing support point of the rocker arm In a variable valve operating apparatus for an internal combustion engine that changes a valve lift of an engine valve by changing a contact position with respect to the driving valve, a rolling bearing member is interposed between an outer peripheral surface of the driving cam and an inner peripheral surface of one end of a link arm. It is characterized by doing.

Therefore, according to the present invention, the frictional resistance between the drive cam and one end of the link arm is greatly reduced by the rolling bearing member interposed between the drive cam and the link arm, so that the drive cam is always smooth. Not only can rotation be obtained, but also the variation in the control shaft torque characteristics can be greatly reduced.
Stable rotation position control of the control shaft becomes possible.

According to a second aspect of the present invention, the rolling bearing member includes a substantially annular retainer, and a plurality of rollers which are held by the retainer and directly contact the outer peripheral surface of the drive cam and the inner peripheral surface of one end of the link arm. And a needle.

According to the present invention, since the inner peripheral side of each needle roller is in direct contact with the outer peripheral surface of the drive cam, and the outer peripheral side of each needle roller is in direct contact with the inner peripheral surface of one end of the link arm, the outer race is held. There is no need to provide such a device. Therefore, it is not necessary to increase the outer diameter of one end of the link arm. Therefore, it is possible to prevent an increase in the size of one end of the link arm, and it is easy to avoid interference with the control shaft.

The invention according to claim 3 is characterized in that the drive shaft and the drive cam are formed separately, the drive cam is fixed to the drive shaft, and the drive cam is formed of a wear-resistant material.

According to the present invention, since the drive cam is formed of a separate wear-resistant material while securing the strength of the shaft portion, the occurrence of wear on the outer peripheral surface, which is the rolling contact surface with the needle roller, is suppressed. The overall durability can be improved.

The invention according to claim 4 is characterized in that the other end of the rocker arm and the swing cam are mechanically linked by a link rod.

According to the present invention, it is possible to mechanically restrict excessive swinging of the swing cam at the time of high engine rotation by the link rod, thereby preventing the swing cam from colliding with the rocker arm, As a result, it is possible to prevent an impact input from acting on the control shaft through the rocker arm, and
The control shaft torque characteristics in the high rotation range can also be stabilized.

According to a fifth aspect of the present invention, the rolling bearing member is fitted and held on the outer peripheral surface of the driving cam, and the retainer for the rolling bearing member cooperates with one side surface formed on the driving cam. It is characterized in that a holding member for clamping is provided.

Accordingly, since the retainer of the rolling bearing member is sandwiched between the holding member and one side surface formed on the drive cam, the axial positioning of the rolling bearing member is facilitated.

According to a sixth aspect of the present invention, a second rolling bearing member is provided between a holding hole substantially at the center of the rocker arm and the control cam rotatably held in the holding hole. Features.

Since the frictional resistance between the control cam and the rocker arm can be greatly reduced by the second rolling bearing member, the rotating torque which the control cam receives from the rocker arm is also greatly reduced. The rotation position control of the shaft can be further stabilized.

[0025]

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 according to this embodiment includes two intake valves per cylinder and a variable mechanism that varies a valve lift amount of each intake valve according to an engine operating state.

That is, as shown in FIGS. 1 and 2, the variable valve apparatus comprises a pair of intake valves 12, 1 slidably provided on a cylinder head 11 via a valve guide (not shown).
2, a hollow drive shaft 13 rotatably supported by a bearing 14 above the cylinder head 11, and one drive cam 15, which is an eccentric rotary cam fixed to the drive shaft 13 by a connecting pin 40, Each of the intake valves 12, 1 is slidably supported by an outer peripheral surface 13a of the drive shaft 13, and slidably contacts a valve lifter 16, 16 disposed at an upper end of each of the intake valves 12, 12.
Swing cams 17 and 17 for opening operation of the driving cam 15 and the driving cam 15
And the swing cams 17, 17, the drive cam 1
The transmission mechanism 18 includes a transmission mechanism 18 that transmits the rotational force of the transmission 5 as the oscillating power of the oscillating cams 17, and a variable mechanism 19 that changes the operating position of the transmission mechanism 18.

The drive shaft 13 is arranged 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 drive shaft 15 is formed of a high-strength material.

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.

The drive cam 15 is integrally formed of a wear-resistant material, and has a substantially ring shape, as shown in FIG. 3, and is provided integrally with an annular cam body 15a and an outer end surface of the cam body 15a. 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. are doing. The drive cam 15 is inserted through the drive shaft 13 through the drive shaft insertion hole 15c, is connected and fixed by the connection pin 40, and has one side surface of the cylindrical portion 15b on the cam body 15a side. A crescent-shaped plane portion is formed. Further, as shown in FIG. 1, the drive cam 15 rotates in a counterclockwise direction (arrow direction) in FIG.

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.

As shown in FIGS. 1, 7, and 8, the swing cams 17, 17 have a substantially raindrop shape, and a drive shaft 13 is inserted into a substantially cylindrical base end portion 20 so as to be rotatable. A support hole 20a to be supported is formed to penetrate, and a pin hole 21a is formed to penetrate one end of the cam nose portion 21 side. Also, the cam surface 2 is provided on the lower surface of the swing cam 17.
The cam surface 22 is formed with a base circular surface 22a on the base end portion 20 side and a cam nose portion 21 from the base circular surface 22a.
Ramp surface 22b extending in an arc shape on the side and the ramp surface 22b
And a lift surface 22c that is continuous with the top surface 22d of the maximum lift that is provided on the tip end side of the cam nose portion 21.
The base circular surface 22a, the ramp surface 22b, the lift surface 22c, and the top surface 22d abut on a predetermined position on the upper surface 16a of each valve lifter 16 according to the swing position of the swing cam 17.

That is, in view of the valve lift characteristics shown in FIG. 5, the predetermined angle range θ1 of the base circular surface 22a is a base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the ramp surface 22b is a so-called ramp section. Further, the predetermined angle range θ3 from the ramp section θ2 of the ramp surface 22b to the top surface 22c is set to be the lift section. An annular holding member 42 is provided between one end surface of the base end portion 20 of the swing cam 17 and the drive cam 15. The holding member 42 has an outer diameter substantially the same as the outer diameter of the cylindrical portion 15b of the drive cam 15, and is fitted and held on the drive shaft 13 via a central hole 42a.

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
7 is provided.

As shown in FIG. 1, the rocker arm 23 has a cylindrical base at the center thereof rotatably supported by a control cam 33 to be described later via a support hole 23c. A pin 2 is provided at one end 23a protruding from the outer end of the cylindrical base.
6 is formed through the pin hole, while the other end 23b projecting from the inner end of the base portion is provided with a pin hole into which a pin 27 connected to one end 25a of the link rod 25 is fitted. Are formed.

The link arm 24 has a base end 24a which is a relatively large-diameter annular end and a base end 2a.
And a projecting end 24b, which is the other end protruding at a predetermined position on the outer peripheral surface of the driving cam 15a. A needle bearing 43 is provided on the outer peripheral surface of the cam body 15a of the driving cam 15 at the center position of the base end 24a. The protruding end 24b is formed with a pin hole through which the pin 26 is rotatably inserted. The shaft center 26 a of the pin 26 is connected to one end 23 of the rocker arm 23.
It is a pivot point with a.

Further, as shown in FIG. 1, 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, 25d through which the ends of the pins 27, 28 press-fit into the respective pin holes 1 are rotatably inserted are formed.

At one end of each of the pins 26, 27, and 28, a snap ring (not shown) is provided to restrict the axial movement of the link arm 24 and the link rod 25.

The cam body 15 of the driving cam 15
A needle bearing 43 which is a rolling bearing member is interposed between a and the inner peripheral surface 24c of the base end portion 24a of the link arm 24 fitted to the outer peripheral surface 15d of the cam body 15a. As shown in FIG. 6, the needle bearing 43 includes an annular holder 44 and a plurality of needle rollers 45 rotatably held by the holder 44. FIG. 6 shows only about a half circumference of the needle bearing 43 for easy understanding, but is actually formed in an annular shape.

The retainer 44 has a flat plate annular shape, and is formed with a plurality of elongated rectangular retaining holes 44a along the width direction at equal intervals in the circumferential direction. On the other hand, each needle roller 4
5 is rotatably held in each holding hole 44a, each inner peripheral edge is in direct contact with the outer peripheral surface 15d of the cam body 15a in a freely rolling manner, and each outer peripheral edge is an inner peripheral surface of the base end portion 24a. 2
4c is in direct contact with the rolling member 4c.

As shown in FIG. 4, the entire needle bearing 43 is held by the outer peripheral surface of the cam body 15a. It is clamped in the direction of the drive shaft 13 by the side surface 42a. Here, the driving cam 15
Since both the holding member 42 and the holding member 42 are formed of a wear-resistant material, the occurrence of wear is suppressed even when the holding member 42 slides on the holder 44.

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.
And a control cam 33 serving as a rocking fulcrum of the control.

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 29 (not shown) provided at one end 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 33a, as shown in the figure.

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

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 controlled via the electromagnetic actuator by a control signal from the controller 30.
Is driven to rotate clockwise. Therefore, the control cam 33
The axis P1 is the axis P2 of the control shaft 32 as shown in FIG.
The thick portion 33a is separated from the drive shaft 13 in the upward direction by being held at the rotation angle position at the upper left from the drive shaft 13. Therefore, the entire rocker arm 23 moves upward with respect to the drive shaft 13.
, The cam nose portion 21 is forcibly pulled up slightly and the whole is turned counterclockwise.

Therefore, as shown in FIGS. 7A and 7B, when the drive cam 15 rotates and pushes up one end 23 a of the rocker arm 23 via the link arm 24, the lift amount is changed by the swing cam 17 via the link rod 25. And the lift amount L1 is transmitted to the valve lifter 16 in FIG.
As shown in FIG.

Therefore, in such a low-speed and low-load region, as shown in FIG. 9, the valve lift becomes sufficiently small, the friction is reduced, and the opening timing of each intake valve 12 is delayed, so that the valve overflow with the exhaust valve occurs. The wrap is smaller. 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 a high engine high load state, the control shaft 32 is rotated counterclockwise by the electromagnetic actuator in accordance with the control signal from the controller. Therefore, as shown in FIGS.
However, the control cam 33 is rotated counterclockwise from the position shown in FIG. 7 to move the axis P1 (thick portion 33a) downward. Therefore, the rocker arm 23 moves in the direction of the drive shaft 13 (downward) as a whole, and the other end 23 b pushes the cam nose portion 21 of the swing cam 17 downward via the link rod 25, thereby causing the rocker arm 23 to swing. The entire moving cam 17 is rotated clockwise by a predetermined amount.

Therefore, 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 is shown in FIG.
It moves to the right direction position (the lift part 22d side) as shown in A and B. For this reason, as shown in FIG.
Rotates and pushes up one end 23a of the rocker arm 23 via the link arm 24, the lift amount L2 of the valve lifter 16 with respect to the valve lifter 16 increases as shown in FIG. 8A.

Therefore, in such a high-speed, high-load region, the cam lift characteristic becomes larger than that in a low-speed, low-load region, and as shown in FIG. 9, the valve lift increases, and the opening timing of each intake valve 12 is advanced. At the same time, the closing time is delayed.
As a result, the intake charging efficiency is improved, and a sufficient output can be secured.

According to the present embodiment, the driving cam 1
Since the needle bearing 43 is interposed between the base 5 and the base end 24a of the link arm 24, the friction coefficient μ between the outer peripheral surface 15d of the cam body 15a and the inner peripheral surface 24c of the base 24a is sufficiently reduced. FIG. 11 is a graph in which the torque acting on the control shaft when μ is changed is calculated as the horizontal shaft drive shaft angle. When the needle bearing is not used, the variation in the friction coefficient μ becomes large, There is a large variation in the range of the solid line and the maximum dashed line. If a needle bearing is used, the coefficient of friction μ becomes sufficiently small, so that it varies only within the range between the solid line and the dashed line. Therefore, the driving cam 1
Not to mention that smooth rotation of the control shaft 5 can be obtained at all times, and the occurrence of variations in the torque characteristics of the control shaft is prevented.

That is, for example, as shown in FIG. 1, when the intake valves 12, 12 open the maximum lift region, the spring force of the valve spring acts on the swing cam 17 via the valve lifter 16 as Fs. whereby moment M ₁ in the counterclockwise direction is applied. Due to this M _1, a reaction force F _{1 in the} direction connecting the shaft centers 27 a, 28 a of both pins 27, 28 of both ends 25 a, 25 b of the link rod 25 acts on the link rod 25 via the pin 28, and the rocker arm 23 This F ₁ acts on the one end 23 a via the pin 27. Thus, rocker arm 23, the F ₁ by the swing fulcrum of the rocker arm 23 undergoes a counterclockwise moment but, F ₂ acts through a pin 26 to the other end portion 23b of rocker arm 23, and the moment Will be balanced.

Next, considering the direction of the F _2, this F ₂ is needle bearing 43 as described above
As shown in FIG. 1, the friction coefficient μ largely passes through the center Y of the drive cam 15 and the axis 26 a (pivot point) of the pin 26 that links the projecting end 24 b of the link arm 24 and the rocker arm 23. It acts in a direction substantially along the straight line Q. Further, the link arm pressing point P is also located substantially on this straight line. As a result, nearly constant, the control shaft center of the reaction force Fc without the force F ₁ and the pressing force F ₂ and the receiving by the direction of the reaction force Fc acting on the control cam 33 axial center P1 (arrow) is varied arm t of the moment for the P ₂ is always substantially constant. For this reason, the torque characteristic of the control shaft 32 is changed as shown in FIG.
Only varies between the solid line μ = 0 and the dot-dash line (μ: the maximum value of the rolling bearing, for example, 0.01). Although FIG. 1 illustrates the case where the straight line connecting the drive shaft 13 axis X and the drive cam center Y coincides with the straight line Q at the moment of the maximum lift, the effect is the same for another drive shaft phase.

As a result of the stabilization of the torque of the control shaft 32, the rotation position control of the control shaft 32 by the electric actuator 29 can be stabilized. For example, the lift control from the maximum lift region to the minimum lift region can be stabilized. . Therefore, the valve lift control by the smooth and stable operation of the variable mechanism 19 according to the engine operating state can be obtained, and the engine performance can be sufficiently exhibited.

In the needle bearing 43, each needle roller 45 is held only by the holder 44,
Since the inner and outer peripheral edges are directly in rolling contact with the outer peripheral surface 15d of the cam body 15a of the drive cam and the inner peripheral surface 24c of the base end 24a of the link arm 24, another member such as an outer race becomes unnecessary. As a result, an increase in the number of parts can be suppressed, and it is not necessary to increase the outer diameter of the link arm base end portion 24a, so that the entire device can be made compact while preventing interference between the link arm 24 and the control shaft 32 and the like. .

Further, when the needle bearing 43 is assembled to the driving cam 15 or the like, the retainer 44 is sandwiched between the one side surface 41a of the driving cam and the one side surface 42a of the holding member 42, so that the positioning in the axial direction is easy. become.

FIG. 10 shows a second embodiment of the present invention.
Assuming the configuration of the first embodiment, the rocker arm 23
A second needle bearing 46 as a different rolling bearing member is interposed between the inner peripheral surface of the support hole 23c and the outer peripheral surface of the control cam 33. The second needle bearing 46 is basically composed of a retainer 47 and a needle roller 48 in the same manner as the first needle bearing 43 described above, but free movement in the axial direction (thrust direction) is not shown. Is regulated by the regulation member.

Therefore, according to this embodiment, since the frictional resistance between the cylindrical base of the rocker arm 23 and the control cam 33 can be greatly reduced, the relative rotation between the control cam 33 and the rocker arm 23 is always smooth. As a matter of course, the rotational alternating torque that the outer periphery of the control cam 33 receives from the rocker arm 23 can be greatly reduced. Therefore,
It is possible to further prevent the torque fluctuation of the control shaft 32 from occurring, and to further stabilize the rotational position control of the control shaft 32.

The present invention is not limited to the configuration of the above-described embodiment. For example, the predetermined support shaft on which the swing cam 17 swings may be different from the drive shaft. It is needless to say that if the drive shaft is also used as in the embodiment, the number of parts can be reduced and the device can be made compact.

[0060]

As is apparent from the above description, claim 1
According to the described invention, the frictional resistance between the drive cam and the inner peripheral surface at one end of the link arm is greatly reduced by the rolling bearing member, so that the drive cam can always be smoothly rotated at all times. Variations in torque characteristics can be greatly reduced, thereby enabling stable control of the rotational position of the control shaft. Therefore, the valve lift control can be stabilized,
The engine performance according to the operation state can be sufficiently exhibited.

According to the second aspect of the present invention, since the inner and outer peripheral edges of the needle roller held by the retainer are brought into direct rolling contact with the outer peripheral surface of the drive cam and the inner peripheral surface of one end of the link arm, the outer race and the like are removed. This eliminates the need for an increase in the number of parts and eliminates the need to increase the inner diameter of one end of the link arm, thereby achieving compactness while avoiding interference with the control shaft.

According to the third aspect of the invention, the occurrence of wear on the outer peripheral surface of the drive cam is also prevented, and the durability can be improved.

According to the fourth aspect of the present invention, the link rod can mechanically suppress excessive swinging of the swing cam at the time of high engine rotation, so that the swing cam may collide with the rocker arm. It can also stabilize the torque characteristics of the control shaft in the high rotation range.

According to the fifth aspect of the present invention, since both ends of the retainer are sandwiched between one side formed on the driving cam and one side of the holding member, the axial positioning of the rolling bearing member is facilitated. .

According to the sixth aspect of the present invention, the frictional resistance between the control cam and the rocker arm can be greatly reduced by the second rolling bearing member. Is also greatly reduced, and the rotational position control of the control cam and the control shaft can be further stabilized.

[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. 2;

FIG. 2 is a perspective view of a main part of the embodiment.

FIG. 3 is a perspective view of a drive cam provided in the embodiment.

FIG. 4 is a partial sectional view of the embodiment.

FIG. 5 is a profile characteristic diagram of a cam surface of the swing cam.

FIG. 6 is a partial perspective view showing a needle bearing provided in the embodiment.

FIG. 7A is an operation explanatory view showing a valve open state at the time of a minimum lift. B is an operation explanatory view showing a valve closed state at the time of the minimum lift.

FIG. 8A is an operation explanatory view showing a valve open state at the time of a maximum lift. B is an operation explanatory view showing a valve closing state at the time of the maximum lift.

FIG. 9 is a valve lift characteristic diagram of the embodiment.

FIG. 10 is a sectional view showing a second embodiment of the present embodiment.

FIG. 11 is a characteristic diagram comparing and showing frictional resistance between the drive cam and the link arm of the variable valve apparatus according to the first embodiment and the prior application.

FIG. 12 is a sectional view showing a conventional variable valve operating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Intake valve 13 ... Drive shaft 15 ... Drive cam 15a ... Cam main body 15d ... Outer peripheral surface 17 ... Swing cam 22 ... Cam surface 23 ... Rocker arm 24 ... Link arm 24a ... Base 24c ... Inner peripheral surface 25 ... Link rod 26 ... Pin 32: Control shaft 33: Control cam 43: Needle bearing 46: Second needle bearing

Continued on the front page (72) Inventor Seinosuke Hara 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. (72) Inventor Keisuke Takeda 1370 Onna, Atsugi-shi, Kanagawa Prefecture Unicity Jex Corporation

Claims (6)

[Claims] An oscillating cam which rotates in synchronization with a crankshaft of an engine and has a driving cam provided on an outer periphery thereof, and a oscillating cam which is swingably supported by a predetermined support shaft to open and close an engine valve. A link arm having an annular one end slidably fitted to the outer periphery of the drive cam; and a control shaft disposed substantially parallel to the drive shaft, the swing arm being swingably provided, one end of the link arm being provided with the link. A rocker arm rotatably linked to the other end of the arm and the other end linked to the oscillating cam; and a rocker arm having an axis eccentrically fixed to the outer periphery of the control shaft, the rocker arm corresponding to the rotational position of the control shaft. A control cam for changing the swing fulcrum of the rocker arm, and changing the contact position of the cam surface of the swing cam with the engine valve according to the change of the swing fulcrum of the rocker arm, thereby making the valve lift of the engine valve variable. A variable valve device for an internal combustion engine, Variable valve device for an internal combustion engine, characterized in that the rolling bearing member is interposed between the outer peripheral surface and the end portion inner peripheral surface of the link arm. 2. The rolling bearing member comprises a substantially annular retainer and a plurality of needles held by the retainer and directly in rolling contact with an outer peripheral surface of a driving cam and an inner peripheral surface of one end of a link arm. The variable valve train for an internal combustion engine according to claim 1, wherein 3. The drive shaft and the drive cam are formed separately, and the drive cam is fixed to the drive shaft, and the drive cam is formed of a wear-resistant material.
A variable valve train for an internal combustion engine according to claim 1. 4. The variable valve apparatus for an internal combustion engine according to claim 1, wherein the other end of the rocker arm and the swing cam are mechanically linked by a link rod. 5. The rolling bearing member is fitted and held on an outer peripheral surface of the driving cam, and cooperates with one side surface formed on the driving cam to clamp a retainer of the rolling bearing member in a driving shaft direction. A holding member is provided.
5. The variable valve operating device for an internal combustion engine according to any one of 4. 6. A rolling bearing according to claim 1, wherein a second rolling bearing member is provided between a holding hole substantially at the center of said rocker arm and said control cam rotatably held in said holding hole. 6. The variable valve train for an internal combustion engine according to any one of claims 1 to 5.