JPH11264307A - Variable valve train for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To variably control a valve timing and a valve lift, suppress transverse and heightwise size increase of a device for downsizing, and improve mountability on an engine. SOLUTION: This device has a drive shaft 13 integrated with a driving cam 15, a rocker arm 18 oscillated by the rotation of the driving cam 15, and an oscillation cam 17 which is oscillated due to the oscillation of the rocker arm 18 through a link member 20. Intake valves 12, 12 are opened and closed by the oscillation of the oscillation cam 17, while a support arm 21 is vertically rotate by a driving means 22, for varying a valve lift. The oscillation cam 17 is arranged on the drive shaft 13 coaxially with the driving cam 15. The support arm 21 is arranged in a sideways prostrated state in the widthwise direction of an engine. The rocker arm 18 is arranged in a transverse direction of the drive shaft 13.

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

[0003] Referring to FIG. 13, an outline thereof will be described. A camshaft 2 is provided substantially above the center of an upper deck of a cylinder head 1, and a cam 2 a is integrally provided on an outer periphery of the camshaft 2. ing. Also,
A control shaft 3 is disposed parallel to a side portion of the camshaft 2, and a rocker arm 5 is pivotally supported on the control shaft 3 via an eccentric cam 4. on the other hand,
A swing cam 8 is disposed at the upper end of an intake valve 6 slidably provided on the cylinder head 1 via a valve lifter 7. The swing cam 8 is swingably supported by a support shaft 9 disposed above the valve lifter 7 and in parallel with the camshaft 2, and a cam surface 8 a at the lower end is in contact with the upper surface of the valve lifter 7. . Further, the rocker arm 5 has one end 5a in contact with the outer peripheral surface of the cam 2a and the other end 5b in contact with the upper end surface 8b of the swing cam 8, so that the cam 2
The lift a is transmitted to the intake valve 6 via the swing cam 8 and the valve lifter 7.

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

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

[0006]

However, in the 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 and independently arranged at positions largely separated in the width direction of the engine. For this reason, a large arrangement space for the cam 2a and the swing cam 8 is required.

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

Further, since the rocker arm 5 is disposed above the cam 2a and the swing cam 8, the height of the engine is inevitably increased. This has led to an increase in size and weight.

Further, since the support shaft 9 is required in addition to the camshaft 2, the number of parts is increased, and the center 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 directly swings on the upper end surface 8b of the swing cam 8 to swing the swing cam 8, the pushing point of the rocker arm 5 (the contact position). ) May be detached from the upper end surface 8b of the swing cam 8. Therefore, there are various problems such as a restriction on the position of the swing fulcrum of the rocker arm 5 and a relatively large swing trajectory of the swing cam 8 and, consequently, the valve timing / lift amount of the intake valve 6 cannot be set relatively large.

[0011]

SUMMARY OF THE INVENTION The present invention has been devised in view of the technical problems of the above-mentioned conventional variable valve operating device. A drive shaft having a drive cam fixed to an outer periphery thereof, a swing cam provided to be swingable on the drive shaft and opening an engine valve, and one end rotatably linked to the drive cam and the other end. A rocker arm linked to the end of the swing cam via a link member, a rocker arm disposed substantially horizontally along the width direction of the engine, a base end rotatably supported by the drive shaft and a tip end rocker arm A support arm linked to the swing fulcrum position, a drive unit for rotating the support arm in the vertical direction, and a control unit for controlling the drive unit in accordance with the operating state of the engine. By rotating the Toamu the vertical direction, characterized by variably controlling the lift amount of control the swing position of the swing cam engine valve via the rocker arm and the link member.

Therefore, according to the first aspect of the present invention, 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 is sufficient. In addition, the rocker arm can be downsized, and the mountability of the device on the engine is improved.

According to a second aspect of the present invention, the driving means includes:
A control shaft disposed in parallel with the drive shaft, a control cam fixed to the control shaft, and a control link having one end rotatably linked to the outer periphery of the control cam and the other end linked to the support arm. And an actuator for driving the control shaft to rotate within a predetermined rotation angle range.

Therefore, since the support arm is supported by the control shaft via the control arm and the control cam,
Even if a vertical load is received from the drive cam or the link member via the rocker arm, the stabilizing support by the control arm or the like can prevent rattling and hitting noise.

According to a third aspect of the present invention, the support arm is disposed between the drive cam and the swing cam in a sandwiched state.

Therefore, since the support arm is disposed between the drive cam and the swing cam, the rolling eccentric load transmitted from the rocker arm can be suppressed, and the fall of the support arm with respect to the drive shaft can be restricted. As a result, it is possible to prevent the occurrence of friction and uneven wear due to shoulder contact between the base of the support arm and the drive shaft.

According to a fourth aspect of the present invention, the rocker arm is arranged such that the distance from the center of rotation of the swing cam to the center of swing of the rocker arm is constant.

Therefore, a predetermined angle is defined between a straight line connecting the pivot center of the swing cam to the connection center point of the swing cam and the link member and a straight line passing from the connection center point to the axis of the link member. By arranging it so that it is always bent in a substantially U-shape, the so-called strut is eliminated when the swing cam and the link member bend and extend, particularly at the time of bending from the maximum extension (at the maximum opening). Flexibility is improved.

According to a fifth aspect of the present invention, a rotation direction of the support arm when the engine valve is changed from a large lift region to a small lift region is set to be the same as the rotation direction of the drive shaft. Features.

Accordingly, the rotation of the drive shaft causes the drive cam to rotate, and the swing cam to rotate through the rocker arm and the link member, thereby opening and closing the engine valve. When the support arm is tilted in the same direction as the rotation direction of the drive shaft during the switching control from the range to the small lift range, the timing of starting rocking of the rocker arm by the drive cam is slightly delayed. As a result, the timing of starting the lift of the engine valve by the swing cam is slightly delayed.

According to a sixth aspect of the present invention, the rotation direction of the support arm is set to a direction opposite to the rotation direction of the drive shaft when the engine valve is changed from a large lift region to a small lift region. And

Therefore, contrary to the fifth aspect of the present invention, since the rotation direction of the large lift area of the support arm to the small lift area is opposite to the rotation direction of the drive shaft, the large lift area of the support arm is changed from the large lift area to the small lift area. At the time of the switching control to, the rocker arm starts to swing by the drive cam slightly earlier, and thus the lift start timing of the engine valve by the swing cam is earlier. Therefore, unique valve timing control according to the engine specifications and the like can be obtained.

According to a seventh aspect of the present invention, the rotation direction of the support arm when the engine valve is changed from a large lift area to a small lift area with respect to the rotation direction of the swing cam when the lift of the engine valve rises. Is set in the opposite direction.

Therefore, when switching from the large lift area to the small lift area, first, the support arm is rotated upward by the drive means, and the rocker arm is also moved upward accordingly, but the drive cam is rotated in the opposite direction. Therefore, the rocker arm swing timing is temporarily advanced. Therefore, the swing cam rotates faster in the lift rising direction, and the lift characteristics of the intake valve result in earlier valve opening start timing and later valve closing timing.

[0025]

1 to 5 show a first embodiment of the present invention, which is applied to an internal combustion engine having two intake valves per cylinder.

That is, this variable valve apparatus comprises a pair of intake valves 12, 12 slidably provided on a cylinder head 11 via a valve guide (not shown), and a cylinder head 1.
1. a hollow drive shaft 13 rotatably supported by a cam bearing (not shown) at the upper part;
A drive cam 15 fixed by press fitting or the like and provided on the shaft 13 coaxially with the drive cam 15 while being supported by a bearing 14, and each intake valve 12, 12 is connected via a valve lifter 16, 16. A pair of oscillating cams 1 to be pushed open
And a rocker arm 18 having one end 18a linked to the drive cam 15 via a link arm 19 and another end 18b linked to the swing cams 17 via a link member 20; The portion 21 a is rotatably supported by the drive shaft 13, and the tip 21 b is
Arm 21 connected to the swing fulcrum, and driving means 2 for tilting the support arm 21 within a predetermined angle range.
2 and control means for controlling the drive means 22 in accordance with the engine operating state.

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

As shown in FIG. 4, the driving cam 15 has a substantially ring shape, and has a large-diameter cam body 15a and a cylindrical portion 15 provided integrally on the outer end surface of the cam body 15a.
b, and a drive shaft insertion hole 1
5c is formed through, and the axis X of the cam body 15a is offset from the axis Y of the drive shaft 13 in the radial direction by a predetermined amount. The driving cam 15
Are press-fitted and fixed to the drive shaft 13 on both outer sides not interfering with the valve lifters 16, 16 via drive shaft insertion holes 15 c.

The link arm 19 has an annular base 19a having a relatively large diameter and a protruding end 19b protruding at a predetermined position on the outer peripheral surface of the base 19a. A fitting hole 19c rotatably fitted to the outer peripheral surface of the cam body 15a of the drive cam 15 is formed, while a pin hole 19d through which the pin 23 is rotatably inserted penetrates the protruding end 19b. Is formed. Further, the link arm 19 is disposed in a state of lying down along the width direction of the engine.

The swing cams 17, 17 are shown in FIGS.
As shown in FIG. 5, a support hole 17b is formed through a substantially cylindrical base portion 17a between the two members 17, 17 in which the drive shaft 13 is inserted and rotatably supported. A pin hole 24a is formed through the end 24 located on the other end 18b side of the rocker arm 18. Also, on the lower surface (cam face) of each swing cam 17, 17, a base circular surface 25a on the base 17a side and the base circular surface 25
a, a cam surface 25 b extending in an arc shape from the end 23 to the end edge side, and the base circular surface 25 a and the cam surface 25 b are formed on the respective valve lifters 16 according to the swing position of the swing cam 17. It comes into contact with a predetermined position on the upper surface. That is, from the viewpoint of the valve lift characteristics shown in FIG. 5, the predetermined angle range θ1 of the base circular surface 25a becomes the base circle section as shown in FIG. 1, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 25b becomes the base circle section. This is a so-called ramp section, and a predetermined angle range θ3 from the ramp section θ2 of the cam surface 25b is set to be a lift section.
Further, the swing direction of the swing cams 17, 17 when the lift from the base circle 25a to the end edge of the cam surface 25b rises is set to be opposite to the rotation direction of the drive shaft 13.

The bearing 14 is provided at an upper end of the cylinder head 11 and supports a base 17a between the swing cams 17, 17. A main bracket 14a is provided at an upper end of the main bracket 14a and a control described later is provided. And a sub-bracket 14b that rotatably supports the shaft, and both brackets 14a, 14b are fixed together from above by a pair of bolts 14c, 14c.

As shown in FIG. 1, the rocker arm 18 is formed to be bent in a substantially rectangular shape, and
The upper end of the support arm 21 is disposed on the base 18 c at the center.
1b is rotatably connected via a pin 26, and one end 18a is rotatably connected to a protruding end 19b of the link arm 19 via the pin 23.
The other end 18 b is rotatably connected to one end 20 a of the link member 20 via a pin 27.

The link member 20 is formed in a linear shape having a predetermined length as shown in FIG.
a and 20b are rotatably connected to the other end 18c of the rocker arm 18 and the end 24 of the swing cam 17 via pins 27 and 28.

Then, as shown in FIG. 1, a straight line Z1 connecting the pivot center of the swing cam 17 to the connection center point of the swing cam 17 and the link member 20, and an axis center of the link member 20 from the connection center point. And a straight line Z2 passing therethrough at a predetermined angle θ so as to be always bent in a substantially rectangular shape. At the end of each of the pins 23, 26, and 27, a snap ring 29 that regulates the axial movement of the link arm 19 or the link member 20 is provided.

The support arm 21 is shown in FIGS.
As shown in FIG. 2, the link base 19 has a substantially linear flat plate shape, and is disposed sideways along the width direction of the engine similarly to the link arm 19 and the link member 20, and the cylindrical base end 21a is attached to the base end 21a. Drive shaft insertion hole 21c formed inside
The drive shaft 13 is rotatably supported on the outer peripheral surface of the drive shaft 13 via a pin 26, and the distal end portion 21b has the pin hole 1 of the base 18c of the rocker arm 18 via the pin 26 as described above.
8d is connected so as to be a swing fulcrum. The support arm 21 has a base end 21a having a drive cam 15
And the rocking cam 17. Further, this support arm 21 is
The lift amount of the intake valves 12 and 12 is made variable by rotating the intake valve 12 in the vertical direction, but the rotation direction at the time of control switching from the large lift region to the small lift region is the same as the rotation direction (arrow) of the drive shaft 13. It is set to rotate downward in the direction.

The driving means 22 includes a control shaft 30 that is supported between the main bracket 14a and the sub-bracket 14b of the bearing 14, a control cam 31 integrally fixed to the outer periphery of the control shaft 30, A control link 32 linking a control cam 31 and a support arm 21;
And an electromagnetic actuator (not shown) that controls the rotation of 0.

Each of the control cams 31 has a cylindrical shape and is fixed to the outer periphery of the control shaft 30. The position of the axis P1 is deviated from the axis P of the control shaft 30 by α as shown in FIG. ing.

The control link 32 has a large-diameter annular end 32a rotatably supported on the outer peripheral surface of the control cam 31 through a circular hole 32c, and a small-diameter annular end. The portion 32 b is rotatably connected to the support arm 21 via a pin 33 at a substantially central position in the longitudinal direction.

The control shaft 30 is controlled by an electromagnetic actuator provided at one end so as to rotate within a predetermined rotation angle range. The electromagnetic actuator is provided with a controller (not shown) for detecting an operating state of the engine. It is driven by a control signal from the controller. The controller detects a current engine operation state by calculation or the like based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a water temperature sensor, and outputs a control signal to the electromagnetic actuator.

In the following, the operation of the present embodiment will be described. First, when the engine is at low speed and low load, the electromagnetic actuator is driven to rotate to one side by a control signal from the controller. For this reason, the control cam 31 is held at the lower left rotation position from the axis P2 of the control shaft 16 with the axis P1 as shown in FIG. 1 and FIG.
Move to approach in the direction. Therefore, the support arm 21 is pivoted downward about the base end 21a as shown in the figure, and is held at a substantially horizontal position. Accordingly, the entire rocker arm 18 moves downward, so that the end portions 24 of the respective rocking cams 17 are forcibly pulled up slightly via the link members 20, and the entire rocking arms 17 are moved leftward (counterclockwise). To rotate.

Accordingly, the rotation of the driving cam 15 causes the one end 18 of the rocker arm 18 to be connected via the link arm 19.
When b is pushed up or down, the rocker arm 18 swings around the tip 21b of the support arm 21 as a fulcrum, and the swinging power is transmitted from the other end 18b to the swing cam 17 and the valve lifter 16 via the link member 20. However, the lift amount L1 is relatively small as shown in FIG.

Therefore, in such a low-speed 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 at the time of high speed and high engine load, the electromagnetic actuator is driven to rotate in the opposite direction by the control signal from the controller. Therefore, FIG.
As shown in FIGS. 1A and 1B, the control shaft 30 controls the control cam 31 in FIG.
From the position shown in and 6, rotate clockwise about 180 °,
The axis P1 (thick portion 31a) is moved upward. Therefore, the support arm 21 is pivoted upward around the base end 21a and is held at a pivot position at a predetermined angle. Therefore, the rocker arm 18 is moved upward in its entirety, and the other end 18b pushes the upper end 24 of the swing cam 17 to the right in the drawing via the link member 20 so that the entire swing cam 17 is moved. Is rotated clockwise by a predetermined amount.

Accordingly, as shown in FIG. 7A, the cam surface 25b of the swing cam 17 comes close to the upper surface of the valve lifter 16. Therefore, when the drive cam 17 rotates to push up one end 18a of the rocker arm 18 via the link arm 19, the lift amount L2 of the valve lifter 16 with respect to the valve lifter 16 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 the low-speed and low-load region, as shown by the solid line in FIG.
The opening timing of each intake valve 12 is advanced, while 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
Not only can the opening / closing timing and valve lift of the valve 2 be variable, but also the drive cam 15 and each swing cam 17 are provided coaxially on the drive shaft 13, so that the arrangement space in the engine width direction is sufficiently reduced. be able to.

Further, the support arm 21, the link arm 19, and the link member 20 are all placed sideways,
Therefore, the rocker arm 18 is also connected to the drive shaft 13.
, The space in the vertical direction of the engine can be sufficiently reduced. In particular, since the rocker arm 18 swings in the maximum lift state at a position lower than the height of the sub-bracket 14b, the height of the rocker cover (not shown), that is, the height of the engine, can be sufficiently reduced. And the entire device can be made compact. As a result, the mountability of the device on the engine is improved.
Further, since the device can be provided 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 17 coaxially on the drive shaft 13, a conventional support shaft for supporting the swing cam 17 becomes unnecessary.
As a result, the number of parts can be reduced, and the shaft center of the drive shaft 13 and the swing cam 17 does not deviate from each other. Therefore, a decrease in valve timing control accuracy can be prevented.

Moreover, since each drive cam 15 is offset from each valve lifter 16 and arranged at a position where they do not interfere with each other, the outer shape of each drive cam 15 can be made large and the degree of freedom in designing the outer peripheral surface 15d can be improved. Accordingly, a sufficient lift amount for securing the swing amount of the swing cam 17 can be secured, and a sufficient cam width for reducing the driving surface pressure of the drive cam 15 can be secured.

Further, the drive cam 15 is formed in a ring shape, and the entire outer peripheral surface is formed in the fitting hole 1 of the link arm base 19a.
Since the entire inner peripheral surface of 9c slides, the surface pressure on the outer peripheral surface is dispersed, and the surface pressure can be sufficiently reduced. Therefore, the occurrence of wear between the inner peripheral surfaces of the fitting holes 19c can be suppressed, and lubrication can be easily performed. Further, the degree of freedom in selecting a material for the driving cam 15 is improved with a decrease in the surface pressure, and a material that is easy to process and can be selected at low cost can be selected.

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 17 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, since the rocker arm 18 and the swing cam 17 are linked via the link member 20, even if the rocker ratio of the rocker arm 18 is set to be relatively large, the link state between the rocker arm 18 and the swing cam 17 is set. Is always kept.
Therefore, a large swing angle of the swing cam 17 can be obtained, so that the ramp section θ2 of the swing cam 17 can be increased.
The collision speed between the swing cam 6 and the swing cam 17 can be reduced, and as a result, the generation of driving noise can be suppressed.

Further, the present apparatus has two intake valves 12, 1
The control shaft 30 can also be supported together with the bearing 14 provided between the cylinder heads 2, so that it is possible to mount the control shaft 30 as it is on a conventional internal combustion engine.
1 does not require a change in shape, and can prevent a rise in manufacturing cost. In addition, since the drive shaft 13 can also be located at a position near the camshaft as in the conventional case, it is not necessary to change the shape of the cylinder head in this regard.

Since the support arm 21 is supported by the control shaft 30 via the control link 32 and the control cam 31, the support arm 21 receives a vertical load from the drive cam 15 and the link member 20 via the rocker arm 18. Even if it is received, it is possible to prevent the occurrence of rattling and striking of the upper and lower sides by stable support by the control link 32 and the like.

Referring to FIG. 1, since the support arm 21 is rotatably held by the drive shaft 13, the support arm 21 of the load acting on the drive cam 15, the link member 20, or the rocker arm is included. Is supported by the support arm 21, the control cam 31 only needs to support the turning power of the support arm 21 via the control link 32, and the load acting on the control cam 31 Is reduced. Therefore, the drive of the control cam 31 is facilitated, control responsiveness can be improved, and the actuator can be downsized. Incidentally, in the conventional example, all loads acting on the rocker arm are held by the control cam, and a large control torque is required.

Further, as described above, the straight line Z1 and the straight line Z2
Are arranged so as to be always bent in a substantially U-shape at a predetermined angle θ, so that the swing cam 17 and the link member 2 are
The angle θ between the straight line Z1 and the straight line Z2 becomes substantially constant from the time of the maximum extension in the large lift control shown in FIG. 7A to the time of the maximum extension in the small lift control shown in FIG. The tension phenomenon disappears, and the bending and elongation becomes good. Therefore, the smooth opening and closing operation of the intake valves 12, 12 can be always obtained. This is because, as shown in FIG. 1, for the small lift control, the swing cam 17 is rotated counterclockwise without moving the swing center of the rocker arm 18 away from the center of the drive shaft 13. In order to rotate the rocking center of the rocker arm 18 counterclockwise about the drive shaft 13 while keeping the distance between the centers constant, the rocker arm 18, the link member 20, and the rocking cam 1 are rotated.
This is because the relative positional relationship of 7 can be kept almost constant.

The support arm 21 is connected to the drive cam 1.
5 and the swing cam 17, so that the rolling eccentric load transmitted from the rocker arm 18 to the support arm 21, that is, the support arm 2.
There is little generation of a moment for tilting the drive shaft 1 in the longitudinal direction of the drive shaft 13, and a shoulder contact between the inner peripheral surface of the drive shaft insertion hole 21 c of the base end portion 21 a of the support arm 21 and the outer peripheral surface of the drive shaft 13. It is possible to prevent the occurrence of friction, uneven wear, and the like due to such factors as above, and to obtain stable and smooth rotation (rotation) at all times.

Furthermore, according to the present embodiment, when the engine shifts from the high engine speed high load area to the low engine speed low load area, the support arm 21 is moved from the upper rotation position (large lift amount) shown in FIGS. 7A and 7B. 1, the horizontal rotation position shown in FIG. 6 (small lift amount)
The direction of rotation is the same as the direction of rotation of the drive shaft 13 (drive cam), and is opposite to the direction of rotation of the swing cam 17 when the lift rises. As shown in FIG.
As shown in FIG. 7, the characteristic becomes such that the lift peak point shifts to the delay side. That is, when shifting from the large lift state to the small lift state, first, as described above, the support arm 21 rotates downward along with the downward rotation of the control cam 31, and at this time, the drive cam 15 also moves in the same direction. , The time length from after the top dead center to the start of the lift (rise) becomes long, and the swing start timing of the rocker arm 18 is temporarily delayed. On the other hand, since the rotation direction of the support arm 21 and the rotation direction of the swing cam 17 at the time of lifting the lift are opposite, the lift of the swing cam 17 due to the delay of the swing start timing of the rocker arm 18. There is also a delay in the rise time. Therefore, as shown in FIG. 8, the valve opening timing when shifting from the large lift region to the small lift region is delayed.

For this reason, even if the piston descends to almost half of the stroke during the intake stroke, the intake valve remains closed, and then the intake valve opens, so that the negative pressure generated in the cylinder causes
The intake is rapidly performed, and the flow of the mixed gas in the combustion chamber is increased, so that the combustion can be improved. In particular, it is possible to improve combustion at the time of low speed and low load immediately after the start of a cold machine or at a low temperature.

FIG. 9 shows a second embodiment of the present invention. The basic structure is exactly the same as that of the first embodiment. The direction of rotation of the support arm 21 at the time of switching to the drive shaft 13 is set to the opposite direction, and the swing cam 17 is arranged in the opposite direction. The direction (rotation direction of the drive cam) is set to be the same direction. That is,
The pivoting method of the swing cam 17 at the time of lifting the lift is set to be opposite to the rotating direction of the support arm 21.

Therefore, when switching from the large lift area to the small lift area, first, the support arm 21 is turned upward by the driving means 22 and the rocker arm 1 is turned.
8 also moves upward with this, but since the drive cam 15 is rotating in the reverse direction, the swing timing of the rocker arm 18 is temporarily advanced. Therefore, the swing cam 17 rotates faster in the lift rising direction, and the lift characteristics of the intake valves 12, 12 result in earlier valve opening start timing as shown in FIG. Become.

As described above, since the closing timing of the intake valves 12 and 12 can be greatly changed, the flow rate of intake air into the combustion chamber can be regulated by reducing the effective stroke length of the intake stroke. Therefore, the throttle degree of the throttle valve can be reduced accordingly, and as a result, pump loss can be reduced.

In short, by setting the rotation direction of the drive shaft 13 and the support arm 21 to be the same or opposite, if the arrangement of the swing cam 17 is changed, the opening when switching from the large lift area to the small lift area is performed. Since the valve timing or the valve closing timing can be controlled to advance or retard, not only optimal lift characteristics can be obtained, but also optimal valve timing control according to the specifications of the engine can be obtained.

FIGS. 11 and 12 show a third embodiment of the present invention, in which the structure of the control cam of the driving means 22 is changed, and the control cam 34 is bent in a crank shape with respect to the control shaft 30. At the same time, one end 32a of the control link 32 is connected to the control cam 34 via a bearing bracket 35 with a bolt 36
It is connected rotatably by.

Therefore, the control cam 3 of the first embodiment
It is not necessary to use a large-diameter eccentric arc cam as in 1,
Large eccentricity can be obtained with a compact shape. As a result,
The downsizing of the driving means 22 makes it possible to further reduce the height of the engine.

The present invention is not limited to the configuration of the above-described embodiment. For example, the outer shapes of the two swing cams 17, 17 may be made different to give a lift difference between the two intake valves 12, 12. For example, the effect of increasing the intake swirl effect in one cylinder and improving the combustibility can be obtained.

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

[0068]

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 drive cam and the swing cam are coaxial with the drive shaft. Since it is provided above, the arrangement space in the engine width direction can be made sufficiently small, and the rocker arm does not need to be extended in the engine width direction, so that the entire apparatus can be made compact. As a result, the mountability of the device on the engine is improved.

Further, since the swing cam is provided on the drive shaft together with the eccentric cam, the 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.

In particular, according to the present invention, since the rocker arm is disposed not in the position above the drive shaft but in the lateral direction via the support arm or the like, no vertical swing space is required, and the height of the engine can be sufficiently reduced. It becomes possible to do. As a result, the mountability of the apparatus on the engine is further improved in combination with the space saving in the lateral width direction.

Further, according to the second aspect of the present invention, since the support arm is stably supported on the control shaft via the control link and the control cam, a vertical load can be applied from the drive cam via the rocker arm. Even if received, rattling and hitting sound are prevented.

According to the third aspect of the invention, the rolling eccentric load transmitted from the rocker arm to the support arm is suppressed, and the fall of the support arm with respect to the drive shaft can be restricted. As a result, it is possible to prevent the occurrence of friction, uneven wear, and the like due to shoulder contact between the base of the support arm and the outer peripheral surface of the drive shaft.

According to the fourth aspect of the present invention, the so-called thrust phenomenon at the time of bending and extension between the swing cam and the link member is avoided, so that a smooth bending and extension movement is always obtained. As a result, the opening and closing operation of the engine valve is performed. Become good.

According to the present invention, the opening and closing timing characteristics of the engine valve can be changed according to the specifications of the engine and the like, so that excellent engine performance can be obtained.

[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 a partial cross section of the embodiment.

FIG. 3 is a plan view of the embodiment.

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

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

FIG. 6 is a sectional view taken along the line BB of FIG. 2 showing the operation at low speed and low load.

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 embodiment.

FIG. 9 is a cross-sectional view showing a second embodiment of the present invention.

FIG. 10 is a characteristic diagram of valve timing and valve lift according to the embodiment.

FIG. 11 is a partial view showing a third embodiment of the present invention.

FIG. 12 is a view taken in the direction of the arrow C in FIG. 11 of the embodiment.

FIG. 13 is a sectional view showing a conventional variable valve operating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Cylinder head 12 ... Intake valve 13 ... Drive shaft 15 ... Drive cam 17 ... Swing cam 18 ... Rocker arm 18a ... One end 18b ... Other end 19 ... Link arm 19a ... Base 19b ... Projection end 20 ... Link member 21 ... Support arm 21a ... base end 21b ... tip end 22 ... driving means 25a ... base circular surface 25b ... cam surface 30 ... control shaft 31 ... control cam 32 ... control link Z1, Z2 ... straight line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiko Yamada 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. 72) Inventor Tetsuro Goto, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (7)

[Claims] 1. A rotary drive by a crankshaft of an engine,
A drive shaft having a drive cam fixed to an outer periphery thereof, a swing cam provided to be swingable on the drive shaft and opening an engine valve, and one end rotatably linked to the drive cam and the other end A rocker arm linked to the end of the swing cam via a link member, and a rocker arm arranged substantially horizontally along the width direction of the engine, a base end rotatably supported by the drive shaft, and a tip end of the rocker arm. A support arm linked to the swing fulcrum position, drive means for rotating the support arm in the vertical direction, and control means for controlling the drive means in accordance with an engine operating state; Internal combustion characterized by controlling the swing position of a swing cam via a rocker arm and a link member by vertically rotating the lift amount of an engine valve. Variable valve system of the function. 2. The control device according to claim 1, wherein the driving unit includes a control shaft disposed in parallel with the drive shaft, a control cam fixed to the control shaft, and one end rotatably linked to the outer periphery of the control cam. 2. The variable valve operating device for an internal combustion engine according to claim 1, wherein a portion includes a control link linked to the support arm and an actuator that drives the control shaft to rotate within a predetermined rotation angle range. 3. The variable valve apparatus for an internal combustion engine according to claim 1, wherein said support arm is disposed between said driving cam and said swing cam. 4. The variable valve of an internal combustion engine according to claim 1, wherein a distance from a rotation center point of the rocking cam to a rocking center point of the rocker arm is fixed. apparatus. 5. The rotation direction of the support arm when converting the engine valve from a large lift region to a small lift region,
The variable valve train for an internal combustion engine according to any one of claims 1 to 4, wherein the direction is set in the same direction as the rotation direction of the drive shaft. 6. The rotation direction of the support arm when the engine valve is changed from a large lift region to a small lift region is set to a direction opposite to a rotation direction of the drive shaft. 5. The variable valve device for an internal combustion engine according to any one of 4). 7. The rotation direction of the support arm when converting the engine valve from the large lift region to the small lift region is set to be opposite to the rotation direction of the swing cam when the engine valve lifts up. The variable valve train for an internal combustion engine according to any one of claims 1 to 4, wherein: