JPH11107725A - Variable valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a variable valve system be easily carried on an engine by compacting the variable valve system while variably controlling valve timing and a valve lift and reduce the number of part items. SOLUTION: This valve system is provided with a drive shaft 13 integrally having a ring-like drive cam 15 in the outer periphery, a rocker arm 18 of a nearly unequal angle like shape, which is engaged with a drive cam 15 at one end 18b and with a rocking cam 20 at the other end 18c through a link arm 25 and a link member 26, and the rocking cam 20 transmitting the pressing force of the rocker arm 18, which is transmitted by the rotation of the drive cam 15, to an intake valve 12 through a valve lifter 19. This rocking cam 20 is rockably arranged in a drive shaft 13 coaxially with the drive cam 15, and the eccentric rotation force of the drive cam 15 is transmitted the intake valve 12 through the rocker arm 18 and the link member 26 converted into linear motion by rotatably fitting a fitting hole 25c made in the base section 25a of the link arm 25 in the outer periphery of the drive cam 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As is well known, in order to improve fuel efficiency at low engine low speed and low load, to ensure stable driving performance, and to secure sufficient output by improving intake air filling efficiency at high speed and high load, intake air intake and air intake are controlled. Various valve operating devices for variably controlling the opening / closing timing of an exhaust valve and the valve lift amount according to the engine operating state have been conventionally provided.
No. 137305 is known.

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

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

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

[0006]

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

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

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

Further, since the end 5b of the rocker arm 5 obtains the swing of the rocking cam 8 by pressing the rocking cam 8, the pressing point (abutting position) of the rocker arm 5 is set to the rocking cam 8. There is a risk of leaving from. Therefore, the position of the swing fulcrum of the rocker arm 5 is restricted, and the swing trajectory of the swing cam 8 and thus the valve timing / lift amount of the intake valve 6 cannot be set relatively large.

Further, in this conventional valve operating apparatus, as described above, the upper end face 8b of the rocking cam 8 is always in elastic contact with the other end 5b of the rocker arm 5 by the spring force of the spring 10, and the rocking cam 8, the swing speed of the swing cam 8 becomes extremely high at the time of high engine rotation, and its own inertial mass acts to reduce the spring force of the spring 10. There is a possibility that it may swing excessively in the counterclockwise direction in the figure without being regulated. For this reason, a tapping sound is generated by being temporarily separated from the other end portion 5b of the rocker arm 5, a dancing phenomenon such as a jump of the intake valve 6 is generated, and the control accuracy of the valve timing is reduced. Causes a problem that it is not possible to exert the effect sufficiently.

Further, the spring force of the spring 10
Since the upper end surface 8b is always in elastic contact with the other end 5b of the rocker arm and the cam surface 8a is also constantly in pressure contact with the upper surface of the valve lifter 7 by the relative pressure with the spring force of the valve spring.
a, 8b, the other end 5b, and the upper surface of the valve lifter generate relatively large friction, and wear easily occurs.

[0012]

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems of the above-mentioned conventional variable valve operating system, and has the following features.
The described invention is rotationally driven by the crankshaft of the engine,
A drive shaft having a drive cam fixed to the outer periphery, a rocker arm swinging by rotation of the drive cam linked to one end, and a swing cam linked to the other end of the rocker arm to open the engine valve, A variable valve actuation device for an internal combustion engine, comprising: an actuator for changing a rocking fulcrum of the rocker arm; and control means for driving and controlling the actuator in accordance with an engine operating state. The drive cam is formed in an eccentric ring shape offset from the axis of the drive shaft, and the drive cam and one end of the rocker arm are rotatably linked via a link arm. Is rotatably fitted to the outer peripheral surface of the drive cam and converts the eccentric torque of the drive cam into linear motion and transmits it to the rocker arm. That.

According to a second aspect of the present invention, the other end of the rocker arm and the swing cam are linked by a link mechanism, and the maximum swing range of the rock cam is adjusted by the rocking of the rocker arm through the link mechanism. It is characterized by regulation within the range.

According to a third aspect of the present invention, the linking mechanism comprises:
It is characterized by comprising a pin inserted into a pin hole provided at each of the other end of the rocker arm and the end of the swing cam, and a link member whose both ends are rotatably connected to the two pins. .

The invention according to a fourth aspect is characterized in that the link member is bent in a curved shape so as to be radially separated from the axis of the drive shaft.

According to a fifth aspect of the present invention, the linking mechanism comprises:
An engagement groove formed in the other end of the rocker arm along the longitudinal direction from an outer edge of the other end, and an engagement slide provided in an end of the swing cam and in the engagement groove. And a sliding pin that moves.

The invention according to claim 6 is characterized in that a protruding end protruding from the outer peripheral surface of the base of the link arm is rotatably connected to one end of the rocker arm via a pin.

According to a seventh aspect of the present invention, the swing cam is
The drive shaft is provided coaxially and swingably.

The invention according to claim 8 is characterized in that two engine valves are provided for each cylinder, and a swing cam is arranged corresponding to each of the engine valves.

According to a ninth aspect of the present invention, the profile of the swing cam of one of the two engine valves is different from the profile of the swing cam of the other engine valve. And

According to a tenth aspect of the present invention, the profile of the drive cam on one engine valve side of the two engine valves and the profile of the drive cam on the other engine valve side are different from each other. . .

According to an eleventh aspect of the present invention, the rocker arms are individually provided corresponding to the respective rocking cams, and the rocking cams are rocked independently of each other.

According to a twelfth aspect of the present invention, two swing cams arranged corresponding to the two engine valves are integrally connected.

According to the present invention, the drive cam fixed to the drive shaft is a ring-shaped eccentric cam, and the link arm is rotatably connected to the drive cam, so that the surface pressure between the drive cam and the link arm can be reduced. , Wear and the like can be prevented.

Since the rocker arm and the swing cam are linked by the link mechanism, the valve timing / lift amount can be set relatively large without the rocker arm and the swing cam coming off.

In addition, the other end of the rocker arm and the end of the swing cam are linked by a link mechanism to restrict the swing of the swing cam within the swing range of the rocker arm. Needless to say, excessive swinging of the swing cam can be prevented even during high rotation, and wear of each sliding portion such as the swing cam can be prevented.

Further, since both the drive cam and the swing cam are provided coaxially on the drive shaft, that is, provided together with the drive shaft, the arrangement space in the engine width direction can be made sufficiently small, and the rocker arm is also provided. The size can be reduced, and the mountability of the device on the engine is improved.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. In each of the embodiments, the present invention is applied to an engine having two intake valves per cylinder, and FIG.
FIG. 3 to FIG. 3 show a first embodiment.

That is, in this variable valve operating apparatus, a pair of intake valves 12 and 12 slidably provided on a cylinder head 11 via a valve guide (not shown) and a cam bearing 14 above the cylinder head 11 rotate. A hollow drive shaft 13 freely supported, and the drive shaft 13
, Two driving cams 15 and 15 fixed by press fitting or the like.
A control shaft 16 rotatably supported by the same cam bearing 14 at a position above the drive shaft 13;
6 and a pair of rocker arms 18, 18 swingably supported by a control cam 17, and a pair of rocker arms 18, 18 disposed at upper end portions of the respective intake valves 12, 12 via valve lifters 19, 19 as transmission members. Independent swing cams 20, 20
And The drive cams 15, 15 and the rocker arms 18, 18 are linked by link arms 25, 25, while the rocker arms 18, 18 and the swing cams 20, 20 are linked by link members 26, 26. I have.

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. Torque is transmitted from the shaft.

The cam bearing 14 is provided on the cylinder head 11.
A main bracket 14a provided at an upper end portion of the main bracket 14 and supporting an upper portion of the drive shaft 13; and a sub bracket 14b provided at an upper end portion of the main bracket 14a and rotatably supporting the control shaft 16. 1
4a, 14b are fixed together from above by a pair of bolts 14c, 14c.

As shown in FIG. 4, the two driving cams 15 each have an eccentric ring shape, and include a small-diameter cam main body 15a and a flange portion 15b integrally provided on an outer end surface of the cam main body 15a. The drive shaft insertion hole 15c is formed in the inner axial direction, and the cam body 15a
Is offset from the axis Y of the drive shaft 13 in the radial direction by a predetermined amount. Each of the drive cams 15 is press-fitted and fixed to both sides of the drive shaft 13 via drive shaft insertion holes 15c so as not to interfere with the two valve lifters 19, 19, and the both cam bodies 15a, 15a are fixed. The outer peripheral surfaces 15d, 15d are formed in the same cam profile.

Each of the rocker arms 18 is bent substantially in a crank shape when viewed from a plane as shown in FIG. 3, and a base 18a at the center is rotatably supported by the control cam 17. One end 18b protruding from each outer end of each base 18a has a pin hole 18 into which the pin 21 is press-fitted.
In addition, a pin 28 connected to one end 26a of each link member 26 described below is press-fitted into the other end 18c protruding from each inner end of each cylindrical base 18a. A pin hole 18e is formed.

Each of the control cams 17 has a cylindrical shape and is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is deviated from the axis P2 of the control shaft 16 by α as shown in FIG. doing.

The swing cam 20 is shown in FIGS.
As shown in FIG. 5, a support hole 22a, which has a substantially horizontal U-shape and is rotatably supported by a drive shaft 13 inserted into a substantially annular base end portion 22, is formed therethrough.
A pin hole 23a is formed through an end 23 on the cam nose side located on the other end 18c side of the rocker arm 18.
On the lower surface of the oscillating cam 20, a base circular surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc from the base circular surface 24a to the distal end side of the cam nose are formed. The circular surface 24a and the cam surface 24b abut on a predetermined position on the upper surface of each valve lifter 19 according to the swing position of the swing cam 20. That is, from the viewpoint of the valve lift characteristics shown in FIG. 5, the predetermined angle range θ1 of the base circle surface 24a is the base circle section as shown in FIG. 1, and the predetermined angle range θ2 is from the base circle section θ1 of the cam surface 24b. This is a so-called ramp section, and the cam surface 24b
The predetermined angle range θ3 from the ramp section θ2 is set to be the lift section.

The link arm 25 has an annular base 25a having a relatively large diameter and a protruding end 25b projecting from a predetermined position on the outer peripheral surface of the base 25a. A fitting hole 25c rotatably fitted to the outer peripheral surface of the cam body 15a of the drive cam 15 is formed, while a pin hole 25d through which the pin 21 is rotatably inserted penetrates the protruding end 25b. Is formed.

Further, as shown in FIG. 1, the link member 26 is formed in a linear shape having a predetermined length, and the other ends 26a and 26b of the circular shape have the other end 1 of the rocker arm 18.
8c and each pin hole 18d, 23 of the end 23 of the swing cam 20.
Pin insertion holes 26c and 26d through which the ends of the pins 28 and 29 press-fitted into a are rotatably inserted are formed.
At one end of each of the pins 21, 28, 29, snap rings 30, 31, 32 for restricting the axial movement of the link arm 25 and the link member 26 are provided. A link mechanism is formed by the link member 26 and the pins 28 and 29 pressed into the respective pin holes 18d and 23a.

The control shaft 16 is controlled by an electromagnetic actuator (not shown) provided at one end so as to rotate within a predetermined rotation angle range. The electromagnetic actuator detects an operating state of the engine (not shown). Is driven by a control signal from the controller. The controller consists of a crank angle sensor, air flow meter,
Based on detection signals from various sensors such as a water temperature sensor, the current engine operation state is detected by calculation or the like, and a control signal is output to the electromagnetic actuator.

In the following, the operation of the present embodiment will be described. First, when the engine is at low speed and low load, the electromagnetic actuator is driven to rotate to one side by a control signal from the controller. For this reason, the control cam 17 has the shaft center P1 as shown in FIGS.
As shown in (2), it is held at the upper left rotation position from the axis P2 of the control shaft 16, and the thick portion 17a moves upward away from the drive shaft 13. For this reason, the rocker arm 18
The entirety of the rocking cam 20 moves upward with respect to the drive shaft 13, so that the end of each rocking cam 20 is slightly lifted up via the link member 26, and the entire rocking cam 20 turns to the left. I do.

Therefore, as shown in FIGS. 6A and 6B, when the drive cam 15 rotates and pushes up one end 18 b of the rocker arm 18 via the link arm 25, the lift amount is changed by the swing cam 20 via the link member 26. The lift amount L1 is relatively small as shown in FIG. 6B.

Therefore, in such a low-speed and low-load region, the valve lift becomes small as shown by the broken line in FIG.
The opening timing of each intake valve 12 is delayed, and the valve overlap with the exhaust valve is reduced. 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 electromagnetic actuator is driven to rotate in the opposite direction by the control signal from the controller. Therefore, FIG.
As shown in FIGS. 6A and 6B, the control shaft 16 controls the control cam 17 in FIG.
Is rotated clockwise from the position shown in FIG. 4 to move the axis P1 (thick portion 17a) downward. For this reason, the rocker arm 18 moves in the direction of the drive shaft 13 (downward) as a whole, and the other end 18 c pushes the upper end 23 of the swing cam 20 downward via the link member 26, thereby causing the rocker arm 18 to swing. The entire moving cam 20 is rotated clockwise by a predetermined amount.

Accordingly, the contact position of the lower surface of the swing cam 20 with respect to the upper surface of the valve lifter 19 moves to the left position as shown in FIGS. 7A and 7B. For this reason, when the drive cam 15 rotates as shown in FIG. 7 and pushes up one end 18b of the rocker arm 18 via the link arm 25, the lift amount L2 with respect to the valve lifter 19 increases as shown in FIG. 7B.

Therefore, in such a high-speed and high-load region, the cam lift characteristics are larger than those in a low-speed and low-load region, and the valve lift amount is increased as shown by a 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 described above, in this embodiment, each intake valve 1
In addition to the variable opening / closing timing and the valve lift amount of 2, the drive shaft 15 and the swing cams 20 are provided coaxially on the drive shaft 13, so that the arrangement space in the engine width direction is sufficiently small. can do. Also,
Each rocker arm 18 also does not need to extend in the width direction of the engine, and can be formed in a small shape of a letter right above the drive shaft, so that the entire apparatus can be made compact. As a result, the mountability of the device on the engine is improved. Further, since the device can be mounted according to the current arrangement of the drive shaft 13 without changing the arrangement of the drive shaft 13, the mountability to the engine is also improved in this respect.

Further, by providing the drive cam 15 and the swing cam 20 coaxially on the drive shaft 13, a conventional support shaft for supporting the swing cam 20 becomes unnecessary.
To this extent, the number of components can be reduced, and the shafts of the drive shaft 13 and the oscillating cam 20 do not deviate from each other, so that a decrease in valve timing control accuracy can be prevented.

Further, since each driving cam 15 is arranged offset from each valve lifter 19 and arranged at a position where they do not interfere with each other, the outer shape of each cam 15 can be made large.
The degree of freedom in designing the outer peripheral surface 15a of the cam 15 can be improved, whereby a sufficient lift amount for securing the swing amount of the swing cam 20 can be secured, and the drive surface pressure of the drive cam 15 can be reduced. In this case, a sufficient cam width can be secured.

In particular, the drive cam 15 is formed in a ring shape, and the entire outer peripheral surface is formed in the fitting hole 25 of the link arm base 25a.
Since the entire inner peripheral surface of c is in sliding contact, the surface pressure on the outer peripheral surface is dispersed, and the surface pressure can be sufficiently reduced. Accordingly, the occurrence of wear between the inner peripheral surfaces of the fitting holes 25c can be suppressed, and
Easy lubrication. In addition, the driving cam 1
The degree of freedom in selecting the material of No. 5 is improved, and a material which is easy to process and can be selected at low cost can be selected.

Further, in the present apparatus, the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20 are mechanically linked by a link member 26 or the like which is a link mechanism, so that the maximum swing cam 20 can be moved. Rocker arm 18
Within the swing range of In other words, the rocking cam 20 is linked by the link member 26 to directly transmit the pushing and pulling forces of the other end portion 18b of the rocker arm 18 and restrict the rocking of the rocker arm 18 beyond the rocking range. Is done. For this reason, even when the engine is running at a high speed, excessive swinging is reliably prevented by its own inertial mass and the like, so that it is possible to prevent the occurrence of a tapping noise with the rocker arm 18 and the like, and to prevent a decrease in valve timing control accuracy. it can.

Further, since the swing cam 20 does not come into pressure contact with the rocker arm 18 and the valve lifter 19 due to the spring force of the spring as in the prior art, the valve lifter 1
9 can be prevented from occurring.

Further, since the rocker arm 18 and the swing cam 20 are linked via the link member 26 as described above, even if the rocker ratio of the rocker arm 18 is set to a relatively large value, the rocker arm 18 and the swing cam 20 are rotated. Is always maintained. Therefore, by obtaining a large swing angle of the swing cam 20, not only the valve timing / lift amount can be set relatively large but also the swing cam 2
The ramp section θ2 of 0 can be increased, whereby the collision speed between the valve lifter 19 and the oscillating cam 20 can be reduced, and as a result, the generation of driving noise can be suppressed. .

Further, since the present apparatus employs a so-called six-link system as a whole, it is possible to increase the rocker ratio of the rocker arm 18, thereby eliminating the need to set a large offset amount of the drive cam 15 with respect to the drive shaft 13. That is, a large swing angle of the swing cam 20 can be obtained without setting the outer diameter of the drive cam 15 large. As a result, the overall size of the apparatus can be further reduced.

Further, the present apparatus has two intake valves 12, 1
The control shaft 16 can also be supported together with the cam bearing 14 that supports the drive shaft 13 provided between the two, so that the control shaft 16 can be mounted as it is on a conventional internal combustion engine. No change is required, and a rise in manufacturing cost can be prevented. In addition, since the drive shaft 13 can be located at the same position as in the related art, it is not necessary to change the shape of the cylinder.

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

FIGS. 9 to 12 show a second embodiment of the present invention, in which the swing cams 20 and 20 corresponding to the intake valves 12 respectively.
Are integrally connected to each other, thereby sharing the drive cam 15 and the rocker arm 18 as a single unit.

That is, the base ends 22, 22 of the two swing cams 20, 20 are integrally connected, and the rocker arm 18 and the drive cam 15 are provided only on one side. Although it is almost the same as that of the embodiment, a link member 26 is connected to the swing cam 20 on one side. That is, the link member 26 is connected to each end 26a.
Are connected to the other end 18 c of the rocker arm 18 via a pin 33, while the other end 26 b is rotatably connected to the swing cam 20 via a pin 34.

As described above, since the drive cam 15 and the rocker arm 18 can be unified, the number of parts can be greatly reduced, and the size and weight can be reduced.

Further, since the swing cams 20 are integrally connected, the distance L between the support portions of the swing cams 20 supported on the drive shaft 13 can be set relatively long. Therefore, the swing cam 2 is
Since the point of action F of the driving force to 0, 20 is located within the range between the bearing portions L, the swing cams 20, 20, which are caused by the gap between the swing cams 20, 20, and the drive shaft 13.
Can be prevented from tilting. Therefore, the swing cams 20, 20
Contact between the valve lifters 19 and 19 can be prevented.

The outer shape of at least one of the left and right swing cams 20, 20 and / or the cams 15, 15 in the drawing may be different.
A lift difference is given to 2,12. For this reason, the intake swirl effect in one cylinder is increased by such a lift difference, and an effect of improving the combustibility is obtained.

FIG. 13 shows a third embodiment of the present invention, in which a substantially central position of a link member 26 is bent in a V-shape so as to be radially separated from the axis of the drive shaft 13. It is. This prevents the link member 26 from contacting the outer peripheral surface of the drive shaft 13 during the minimum lift control of the intake valve 12 as shown in the figure.
Therefore, the size of the apparatus in the engine width direction can be reduced while securing a sufficient swing angle of the swing cam 20, and the size of the apparatus can be reduced.

FIG. 14 shows a fourth embodiment of the present invention.
This is a modification of the configuration of the linkage mechanism. That is, the rocker arm 18 has the other end 18c extending along the longitudinal direction, and has a notch formed with a two-sided width-like engaging groove 35 from the substantially center of the outer edge of the other end 18c toward the base 18a. Have been. On the other hand, the swing cam 20 has a substantially inverted U-shaped projection 36 integrally formed at the upper end edge of the end 23 on the cam nose side, and a pin hole 37 formed in the projection 36.
, A base end of a slide pin 38 whose one end is slidably engaged with the engagement groove 35 is press-fitted and fixed. Therefore, the other end 18 c of the rocker arm 18 and the swing cam 20 are linked by the engagement groove 35 and the slide pin 38.

Therefore, since the link member 26 as in the first to third embodiments can be eliminated, the entire apparatus can be made compact, and the inertial mass can be sufficiently reduced. Since other configurations are the same as those of the first embodiment, it is needless to say that the same operation and effect can be obtained.

In each of the above embodiments, the case where the device is applied to the intake valve 12 is shown. However, it is also possible to apply the device to the exhaust valve or both the intake and exhaust valves. Instead, the present invention can be applied to a one-valve valve.

[0064]

As is apparent from the above description, according to the present invention, not only the valve timing and the valve lift of the engine valve can be variably controlled, but also the eccentric ring-shaped drive cam is entirely linked. Since the arm is rotatably fitted and connected to the arm, the surface pressure with the link arm can be sufficiently reduced. Therefore, the occurrence of wear between the two can be suppressed and lubrication can be easily performed. Further, as the surface pressure decreases, the degree of freedom in selecting the material of the driving cam is improved, and processing and material cost can be reduced.

According to the second and third aspects of the present invention, not only is the valve timing / lift amount set relatively large, but also the maximum swing range of the swing cam is set within the swing range of the rocker arm by the linkage mechanism. Therefore, even when the engine is running at a high speed, a so-called dance phenomenon such as excessive swinging or jumping of the swinging cam is reliably prevented.
For this reason, a collision due to separation and contact between the swing cam and the rocker arm is avoided, so that a tapping sound is prevented from occurring and a decrease in valve timing control accuracy is also prevented.

Further, since there is no pressure contact between the oscillating cam and the sliding contact portion such as the rocker arm due to the spring force of the spring as in the prior art, it is possible to prevent the sliding contact portion from being worn. Further, since a spring is not required, the degree of freedom of the layout of each component is improved.

According to the fourth aspect of the present invention, the contact between the link member and the drive shaft during the minimum lift control of the engine valve can be avoided by the curved state of the link member. It is possible to reduce the size of the device in the engine width direction while securing the size.

According to the fifth aspect of the present invention, not only the excessive swing of the swing cam is restricted, but also the link member is eliminated, so that the size and weight of the apparatus can be reduced by reducing the number of parts. In addition, the efficiency of the manufacturing operation and the assembly operation can be improved.

According to the sixth aspect of the present invention, since the entire apparatus is of a six-link type, it is possible to increase the rocker ratio of the rocker arm, thereby preventing the outer diameter of the drive cam from increasing. In both cases, a large swing angle of the swing cam can be obtained. As a result, the overall size of the apparatus can be further reduced.

Further, since the existing arrangement of the drive shaft can be used as it is without changing the arrangement of the drive shaft, the mountability of the apparatus on the engine is improved in this respect as well.

According to the seventh aspect of the present invention, since the driving cam and the swing cam are provided coaxially on the drive shaft,
The arrangement space in the engine width direction can be made sufficiently small, and the rocker arm does not need to be extended in the engine width direction, so that the entire device can be made compact. As a result, the mountability of the device on the engine is improved.

Further, since the swing cam is provided on the drive shaft together with the drive cam, a conventional support shaft is not required, so that the number of parts can be reduced, and the drive shaft and the swing cam can be connected to each other. Since there is no displacement of the shaft center, it is possible to prevent a decrease in control accuracy of the valve timing.

According to the ninth and tenth aspects of the present invention, the swirling effect in the cylinder is increased by making the profiles of the two oscillating cams and the two cams of the drive shaft different from each other, and the flammability is improved. Become.

According to the eleventh aspect of the present invention, since the swing cams are independent of each other, the opening / closing timing of both valves can be freely set, and the swirl effect can be obtained similarly to the ninth and tenth aspects of the present invention. In addition to this, optimal intake and exhaust control according to the engine operating state can be performed.

According to the twelfth aspect of the present invention, the drive cam and the rocker arm can be shared by connecting the two swing cams, so that the number of parts, the size, and the weight can be reduced. .

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2, showing a first embodiment of the present invention.

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

FIG. 3 is a plan view of the embodiment.

FIG. 4 is an exemplary perspective view showing a drive cam provided in the embodiment;

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

FIGS. 6A and 6B show the operation at low speed and low load;
B sectional drawing.

FIGS. 7A and 7B show the operation at high speed and high load;
B sectional drawing.

FIG. 8 is a characteristic diagram of valve timing and valve lift according to the present embodiment.

FIG. 9 is a side view showing a second embodiment of the present invention in partial cross section.

FIG. 10 is a plan view of the embodiment.

FIG. 11 is a sectional view taken along line CC of FIG. 9;

FIG. 12 is a sectional view taken along line DD of FIG. 9;

FIG. 13 is a sectional view showing a third embodiment of the present invention.

FIG. 14 is a sectional view showing a fourth embodiment of the present invention.

FIG. 15 is a sectional view showing a conventional valve train.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Cylinder head 12 ... Intake valve 13 ... Drive shaft 15 ... Drive cam 16 ... Control shaft 17 ... Control cam 17a ... Thick part 18 ... Rocker arm 18b ... One end 18c ... The other end 19 ... Valve lifter (transmission member) 20 ... Swinging cam 23 ... End 24a ... Base circular surface 24b ... Cam surface 25 ... Link arm 25a ... Base 25b ... Protrusion end 25c ... Fit hole 26 ... Link member 26a, 26b ... Ends 21,28,29 ... Pin

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keisuke Takeda 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. (72) Inventor Tsutomu 1370 Onna, Atsugi-shi, Kanagawa Prefecture Unicity Jex Co., Ltd. (72) Inventor Akira Onuki 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisex Jex Co., Ltd. (72) Inventor Shin Shinmura 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisex Jex Inc. (72) Inventor Shunichi Aoyama Kanagawa Nissan Motor Co., Ltd. (2) Takara-cho, Kanagawa-ku, Yokohama-shi (72) Inventor Shinichi Takemura 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Tetsuro Goto Takaracho, Kanagawa-ku, Yokohama, Kanagawa No. Nissan Motor Co., Ltd. (72) Inventor Katsuya Mogi Yokohama City, Kanagawa Prefecture Nagawa-ku Takaracho Address 2 Nissan-car Co., Ltd.

Claims (12)

[Claims] 1. A rotary drive by a crankshaft of an engine,
A drive shaft having a drive cam fixed to the outer periphery, a rocker arm swinging by rotation of the drive cam linked to one end, and a swing cam linked to the other end of the rocker arm to open the engine valve, A variable valve apparatus for an internal combustion engine, comprising: an actuator that changes a rocking fulcrum of the rocker arm; and control means that drives and controls the actuator in accordance with an engine operating state. The drive cam is formed in an eccentric ring shape offset from the axis of the drive shaft, and the drive cam and one end of the rocker arm are rotatably linked via a link arm. Rotatably fitted to the outer peripheral surface of the drive cam to convert the eccentric torque of the drive cam into a linear motion and transmit it to the rocker arm. Variable valve gear for internal combustion engines. 2. The rocker arm is linked with the swing cam by the other end of the rocker arm by a linkage mechanism, and the maximum swing range of the rocker cam is restricted to the rocker arm swing range through the linkage mechanism. The variable valve apparatus for an internal combustion engine according to claim 1, wherein: 3. A link comprising: a pin inserted into a pin hole provided in each of the other end of a rocker arm and an end of a swing cam; and a link having both ends rotatably connected to the two pins. 3. The variable valve train for an internal combustion engine according to claim 2, wherein the variable valve train comprises a member. 4. A variable valve operating apparatus for an internal combustion engine according to claim 3, wherein said link member is bent in a curved shape so as to be radially separated from an axis of said drive shaft. 5. An engaging groove formed in the other end of the rocker arm along the longitudinal direction from an outer edge of the other end of the rocker arm, and an end of the swing cam. 3. A variable valve train for an internal combustion engine according to claim 2, wherein said slide valve is configured to slide into said engagement groove. 6. The link arm according to claim 1, wherein a protruding end protruding from an outer peripheral surface of a base of the link arm is rotatably connected to one end of the rocker arm via a pin. A variable valve train for an internal combustion engine according to claim 1. 7. The drive cam according to claim 1, wherein the swing cam is provided coaxially and swingably on the drive shaft.
7. The variable valve train for an internal combustion engine according to any one of claims 6 to 6. 8. The internal combustion engine according to claim 1, wherein two engine valves are provided for each cylinder, and a swing cam is arranged corresponding to each of the engine valves. Variable valve gear. 9. The oscillating cam on one engine valve side of the two engine valves and the oscillating cam on the other engine valve side have different profiles from each other. Variable valve train for an internal combustion engine. 10. The profile of a drive cam on one engine valve side of the two engine valves and the profile of a drive cam on the other engine valve side of each of the two engine valves are different from each other. Variable valve train for an internal combustion engine. 11. The rocker arm according to claim 8, wherein said rocker arms are individually provided corresponding to said respective rocking cams, and said rocking cams are rocked independently of each other.
The variable valve device for an internal combustion engine according to any one of claims 10 to 10. 12. The variable valve operating apparatus for an internal combustion engine according to claim 8, wherein two swing cams arranged corresponding to each of said two engine valves are integrally connected.