JP3354785B2 - Intake and exhaust valve drive control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the opening and closing of an intake valve and an exhaust valve according to the operating state of an internal combustion engine by rotating a cylindrical camshaft arranged around the drive shaft at an unequal speed relative to the drive shaft. More particularly, the present invention relates to an intake and exhaust valve drive control device for an internal combustion engine in which a valve lift characteristic is controlled by a rotation position of a control shaft having an eccentric cam.

[0002]

2. Description of the Related Art Various types of devices for variably controlling the opening / closing timings and operating angles of intake and exhaust valves have been conventionally provided.
As described in JP-A-306-306 and JP-A-6-185321, those applying the principle of a non-uniform velocity joint are known. This is because a cylindrical camshaft divided for each cylinder is provided on an outer periphery of a drive shaft that rotates in synchronization with rotation of the engine, and a flange portion at an end of the camshaft and a flange portion on the drive shaft side are provided. And a pair of pins that are engaged with the respective engagement grooves are provided in an annular disk interposed between the two flange portions, and the annular disk is provided in a control housing. In this way, while holding rotatably, the annular disk can be eccentric with respect to the camshaft via the control housing, and by controlling the amount of eccentricity,
The valve lift characteristics change.

Further, Japanese Patent Application Laid-Open No. 6-185321 discloses a configuration using an eccentric cam to move the control housing in a direction perpendicular to the axis. That is, a circular cam fitting hole is formed in the control housing, and an eccentric cam formed in the control shaft is rotatably fitted in the cam fitting hole. The control housing is moved by controlling the rotational position of the control shaft by an actuator such as a hydraulic motor.

[0004]

In the configuration using the eccentric cam as described above, the valve spring reaction force acts indirectly on the eccentric cam to rotate the eccentric cam. Considering the time, or the start time when the hydraulic pressure supplied to the hydraulic motor becomes insufficient, it is necessary to regulate the rotation of the control shaft at a predetermined position.

Here, when a hydraulic motor is used as the actuator, the rotation range of the hydraulic motor itself is restricted to a certain angle, so that the rotation angle of the control shaft is necessarily restricted to a certain range. become. However, even if the rotation of the control shaft is regulated on the actuator side in this way, there is always a play in the connection between the actuator and the control shaft and an error in mounting the actuator, so that the position of the control shaft is accurately determined. I can't. Therefore, for example, when the regulation position is made to correspond to the characteristics at the time of idling, the desired idling performance cannot be ensured.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a drive shaft which is disposed over a plurality of cylinders and which rotates in synchronization with the rotation of an engine, and which is rotatably fitted to the outer periphery of the drive shaft. A cylindrical camshaft having a plurality of cams on the outer periphery each of which is adapted to drive an intake / exhaust valve while being divided for each cylinder, and provided at an end of each camshaft in a flange shape. A first flange portion, a second flange portion provided on the drive shaft side so as to face the first flange portion, an annular disk disposed between the two flange portions, respectively, and the annular disk A pair of radially extending engagement grooves for transmitting rotational movement while allowing eccentricity between the two and the two flange portions, and a pair of pins engaging with the engagement grooves; While holding it rotatably, A control housing having an opening formed with a cam fitting hole and a bush fitting hole, and an inner peripheral surface rotatably fitted to the outer periphery of the fixed shaft, and an outer peripheral surface rotating into the bush fitting hole of the control housing. An eccentric bush, which is fitted so as to be able to move the control housing along the direction perpendicular to the axis, and an eccentric cam rotatably fitted in a cam fitting hole of the control housing. A control shaft for moving the control housing along the direction perpendicular to the axis, and an actuator for driving the shaft to rotate so as to change the rotational position of the control shaft; By regulating the rotation of the control shaft to one side, a position regulation is performed at the rotational position of the control shaft at which the valve operating angle is minimized. Equipped with a Tsu path means
The stopper means is provided on the outer periphery of the control shaft.
The projected projection and the cylinder contact the projection.
From the stopper provided on the cam bracket on the head
And the above control shear due to the valve spring reaction force.
The rotational force of the shaft pushes the protrusion and the stopper
It is characterized in that it is configured to act in the direction of attaching .

[0007] In this configuration, the rotational position of the control shaft is directly regulated by the stopper means, and is not affected by play of the connecting portion with the actuator.

[0008] In addition, the stopper means is, Barubusupuri
In the direction in which the valve operating angle becomes smaller due to
The position of the energized control shaft is restricted at the rotational position of the control shaft where the valve operating angle is minimized.

Thus, for example, even if the actuator fails, the valve operating angle does not become smaller than the predetermined minimum angle. If the lift amount is constant, the valve movement becomes steeper as the valve operation angle becomes smaller. However, according to this configuration, the valve operation angle does not excessively decrease, and the valve movement deteriorates. Does not occur.

The invention according to claim 2 further comprises control shaft rotational position detecting means for detecting the rotational position of the control shaft, and learns the control shaft rotational position when the position of the control shaft is regulated. I have.

For example, when the engine is started or the like, the position of the control shaft is regulated by the stopper means. By detecting and learning the rotational position at this time, the influence of individual differences and changes over time can be eliminated.

According to a third aspect of the present invention, the actuator is held at a position immediately before the rotational position to be regulated by the stopper means, so that the driving force of the actuator does not act on the stopper means.

That is, the rotational position of the control shaft is controlled by the actuator in accordance with the engine operating conditions. If the control target is the rotational position to be restricted by the stopper means, the rotational position is actually adjusted to that position. The actuator is not driven, and is controlled to the position just before. Thus, the phenomenon that the actuator keeps pressing the stopper means does not occur.

[0014]

The rotation of the control shaft is reliably restricted by the projection on the outer periphery of the control shaft contacting the stopper of the cam bracket.

According to a fourth aspect of the present invention, the position of the stopper is adjustable.

By adjusting the position of the stopper, the rotational position of the control shaft to be positioned is changed, and the valve lift characteristic is changed.

[0018]

According to the present invention, the rotational position of the control shaft can be regulated to a predetermined position with high accuracy without being affected by play of the connecting portion between the control shaft and the actuator or mounting error of the actuator. Variations in valve lift characteristics under a restricted rotation position, and thus variations in engine performance, can be suppressed.

In particular, even when the actuator is out of order, the valve operating angle is not excessively reduced, and the deterioration of the valve movement can be reliably avoided. Moreover, the rotation of the control shaft
Position can be regulated directly and reliably.

[0020] According to claim 2, similarly to the time of learning can eliminate the influence of such play of the connecting portion, reliably to individual differences and changes over time can be addressed.

According to the third aspect , unnecessary operation of the actuator can be avoided, and the stopper means can be prevented from being worn over time.

[0022]

According to the fourth aspect , the valve lift characteristics at the time of restricting the position of the control shaft and thus the performance of the engine can be easily adjusted.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an intake / exhaust valve drive control device according to the present invention will be described below with reference to the drawings.

This embodiment is an example in which the invention is applied to an intake valve of an in-line multi-cylinder internal combustion cylinder, and as shown in FIG. It is arranged. The drive shaft 2 has a lubricating oil passage 3
1 and has a sprocket (not shown) at one end, and is linked to the crankshaft via a timing chain. A cylindrical camshaft 3 divided for each cylinder is fitted around the outer periphery of the drive shaft 2 so as to be rotatable relative to each other.
Is provided. Each camshaft 3 has a pair of cams 3a for driving an intake valve (not shown), and has a journal portion 3b at an intermediate position between the pair of cams 3a. The journal portion 3b is rotatable with respect to the cylinder head 1. Supported. More specifically, a cam bracket 5 is attached to the partition-shaped bearing portion 1a on the cylinder head 1 side, and the journal portion 3b is rotatably fitted into a cam bearing hole 6 formed therebetween. I have. A short sleeve 7 is fixed to the drive shaft 2 for each cylinder, and a second flange 8 is formed at an end of each sleeve 7 so as to face the first flange 4. I have. An annular disk 9 having an annular shape is interposed between the flange portions 4 and 8.
Is rotatably fitted and held in a circular opening 10 a of the control housing 10.

The first flange portion 4 and the second flange portion 8 are respectively provided with engaging grooves 11, 12 extending in the radial direction.
Are formed. The two engagement grooves 11 and 12 are 18
0 ° different positions. The annular disc 9 has holding holes 13 and 14 (see FIG. 2) penetratingly formed at positions different from each other by 180 °, and the first pin 15 and the second pin 16 are rotatably fitted respectively. I agree. These pins 15 and 16 project in opposite directions to each other, and the tip of the first pin 15 is slidably engaged with the engagement groove 11 of the first flange 4, and the second pin 16 is Are slidably engaged with the engagement grooves 12 of the second flange portion 8. The engagement grooves 11,
The side surfaces of the tips of the pins 15 and 16 that are in sliding contact with 12 are machined into a pair of parallel planes.

The control housing 10 for holding the annular disk 9 has a plate shape along a plane perpendicular to the drive shaft 2 and has a fixed shaft 17 disposed in parallel with the drive shaft 2.
And the control shaft 18 so as to be movable in a direction perpendicular to the axis. That is, as shown in FIG. 2, above the opening 10 a of the control housing 10,
The cam fitting hole 19 and the bush fitting hole 2 each having a circular shape.
The control shaft 18 is inserted through the cam fitting hole 19, and the fixed shaft 17 is inserted through the bush fitting hole 20. A circular eccentric cam 21 is fixed to the control shaft 18 for each cylinder.
The outer peripheral surface of the eccentric cam 21 is slidably fitted in the cam fitting hole 19. An eccentric bush 22 is interposed between the fixed shaft 17 and the bush fitting hole 20. The eccentric bush 22 has an eccentric outer peripheral surface and an inner peripheral surface that are formed in a perfect circle. The inner peripheral surface is rotatably fitted to the fixed shaft 17 and the outer peripheral surface is fitted to the bush. It is rotatably fitted in the hole 20. Therefore, when the control shaft 18 provided with the eccentric cam 21 rotates, the control housing 10 swings up and down in the figure,
The center of the annular disk 9 is the drive shaft 2 and the camshaft 3
It is eccentric from the center.

As shown in FIG. 1, the control shaft 18 is disposed parallel to the drive shaft 2 and is continuous over all the cylinders. One end of the control shaft 18 is a hydraulic actuator 46 of the control mechanism 25 described later. (See FIG. 3). The control shaft 18 is rotatably supported by a bearing hole 23 provided in an upper portion of the cam bracket 5 as shown in FIG. Specifically, the cam bracket 5
Is divided into an upper bracket 5a and a lower bracket 5b along a plane passing through the center of the bearing hole 23,
The bearing hole 23 is formed between the two. The upper bracket 5a and the lower bracket 5b are fastened together to the cylinder head 1 by a pair of bolts 24, 24 passing on both sides.

In this embodiment, the fixed shaft 17 is also continuous over all cylinders, and is fixed to each cam bracket 5.

The above-described variable valve lift characteristic changing mechanism itself includes:
For example, since the configuration is well-known in the above-mentioned Japanese Patent Application Laid-Open No. 6-185321, a detailed description of its operation is omitted, but when the annular disk 9 is concentric with the center of the drive shaft 2 as shown in FIG. If each camshaft 3 is the drive shaft 2
, And a valve lift characteristic along the profile of the cam 3a is obtained. Further, the annular disk 9 is the drive shaft
Eccentric to the center of
Each camshaft 3 rotates unequally with respect to the drive shaft 2. As a result, the valve lift characteristics and the valve operating angle change.

A first oil hole 32 and a second oil hole 33 are formed through the drive shaft 2 and the camshaft 3, respectively, along the radial direction from the lubricating oil passage 31 inside the drive shaft 2. These first and second oil holes 32 and 33 are located at positions that are continuous with each other when they rotate in phase.
The tip of the second oil hole 33 is open at a position corresponding to the cam bearing hole 6 of the cam bracket 5.

That is, the lubricating oil fed to the lubricating oil passage 31 of the drive shaft 2 is supplied to the inner periphery of the cam bearing hole 6 of the cam bracket 5 through the first oil hole 32 and the second oil hole 33, and the camshaft 3 Lubricate between. Further, a part of the lubricating oil is supplied to the sliding contact surface between the drive shaft 2 and the camshaft 3 through the first oil hole 32 to lubricate it.

As shown in FIGS. 3 to 7, the control mechanism 25 includes a hydraulic actuator 46 connected to one end of the control shaft 18 and an electromagnetic actuator 47 for operating the hydraulic actuator 46. .

The hydraulic actuator 46 has a cylindrical casing 49 fixed to a base plate 48 fixed on the cylinder head 1 along the longitudinal direction of the engine.
A rotary vane 50 rotatably housed inside the casing 49; and four hydraulic chambers 51, 51, 52, 52 separated by the rotary vane 50 (see FIGS. 5 to 7). ing.

The casing 49 has both front and rear ends liquid-tightly closed by a disk-shaped front cover 53 and a rear cover 54, and is fixed to the base plate 48 by bolts 55 via the rear cover 54. Further, a pair of bulging partition walls 56 and 57 are fixed to the inner peripheral surface of the casing 49 at left and right opposing positions in the drawing, that is, at right and left opposing positions in the figure by bolts 58 screwed from the radial direction. . The partition walls 56 and 57 are set to be slightly shorter than the axial length of the casing 49, and the U-shaped rubber seal member 5 is fitted in the fitting groove at the top.
9 and 60, and sliding members 61 and 62 made of Teflon are provided on the outer end surfaces of the sealing members 59 and 60, respectively. In addition, the partition walls 56 and 57 have rotating vanes 5 on both sides.
0 are tapered surfaces 56a, 56b, 57 with which both side surfaces abut.
a, 57b are formed.

The rotary vane 50 has a cylindrical wall 50a extending in the center axis direction, and two blades 50b, 50b integrally provided on the outer surface of the cylindrical wall 50a and extending in the direction of the inner diameter of the casing 49. And the blade portions 50b, 50b
The longitudinal length of the casing 49 is set to be slightly shorter than the axial length of the casing 49, and rubber sealing members 63, 63 and the casing 4 are fitted in fitting grooves formed at the outer ends.
9, sliding members 64, 64 made of Teflon which are in sliding contact with the inner peripheral surface.
Is provided.

Each of the hydraulic chambers 51, 51, separated by the rotary vane 50 via the partition walls 56, 57,
52, 52 are arranged above and below inside the casing 49. In other words, the hydraulic chambers 51, 52 and the hydraulic chambers 51, 52 adjacent to each other via the blade portions 50b, 50b are arranged vertically.

On the other hand, the cylindrical wall 50a has one end 50c extending forward through the center hole 53a of the front cover 53.
Is connected to one end 18a of the control shaft 18, and a partition 50d for securing strength is integrally formed on an inner peripheral surface corresponding to the central hole 53a. The cylinder wall 50a is formed with a hydraulic supply passage 65 that is continuous with the inside of the control shaft 18 in the inner axial direction. Further, as shown in FIGS. 4, 5A, 6A, and 7A, the cylindrical wall 50a is disposed on the same plane in the radial direction at the position on the control shaft 18 side, that is, on the front end side. Room 5
1 and the second hydraulic chamber 52 on the lower side.
Supply holes 66a and 67a are formed in the radial direction so as to partially overlap the right bases of the blade portions 50b and 50b in the drawing.

As shown in FIG. 5B, FIG. 6B and FIG. 7B, the hydraulic supply passage 65 and the lower first hydraulic chamber are also provided on the same radial plane at a position near the center from the front end of the cylindrical wall 50a. A third and a fourth connecting the upper and lower hydraulic chambers 52 to each other;
The supply holes 66b, 67b are formed in the radial direction so as to hang over a part of the left base of each of the blades 50b, 50b in the drawing.

Further, each of the supply holes 66a-6a of the cylindrical wall 50a is provided.
4, 5C to 7C at a predetermined position behind
5D to 7D, the hydraulic discharge passage 68, the upper first hydraulic chamber 51 and the lower second hydraulic chamber 52, and the lower first hydraulic chamber 51 and the upper First and second discharge holes 69 communicating with the second hydraulic chamber 52, respectively.
a, 70a, and third and fourth discharge holes 69b to 70b are formed in the same manner as the supply holes 66a to 67b.

As described above, since the supply holes 66a to 67b and the discharge holes 69a to 70b are formed on the same plane at positions opposite to each other by about 180 ° and are sufficiently separated from each other, the opening area of each hole is reduced in the circumferential direction. Can be set large along. The supply holes 66a to 67b and the discharge holes 69a to 70b are
It is formed in a circular shape.

As shown in FIG. 4, the hydraulic supply passage 65 is connected to an oil pump (not shown) through an oil main gallery through a through hole 65a formed in the peripheral wall of the control shaft 18 along the radial direction. Communicating. On the other hand, the hydraulic discharge passage 68 includes an annular groove 68a at the rear end side of the rotary valve 72, which will be described later, which is disposed through the inside of the cylindrical wall 50a,
A space 68b on the inner peripheral side of the base plate 48,
The annular groove 68a is liquid-tightly separated from the hydraulic intake passage 65 by a rotary valve 72. The space 68b communicates with the upper portion of the cylinder head 1 via a drain hole (not shown) formed in the base plate 48.

As shown in FIGS. 3 and 4, the electromagnetic actuator 47 is fixed to a step motor 71 and a distal end of a driving rod 76 of the step motor 71.
A rotary valve 72 rotatably housed and disposed inside the cylindrical wall 50a. The step motor unit 71 has a general structure, and includes an electromagnetic coil 74, a rotor 75, and the like housed in a body 73 fixed to a base plate 48 by bolts 86 via a front end plate 85. The base end of the drive rod 76 is fixed to the rotor 75. The drive rod 76 is connected to the body 7
3 is rotatably supported by ball bearings 77 and 78 provided at the center of the rear and front end plates 85, and the front end is press-fitted and fixed to a fixing hole in a wall of the inner peripheral surface of the rotary valve 72. I have.

The rotary valve 72 has a substantially cylindrical shape, and is provided at the front end of the peripheral wall on the front side of the intermediate wall as shown in FIGS.
7A, the first and second supply holes 66a,
A single first supply passage hole 79 that is appropriately communicated with the front peripheral wall 67a is formed at the rear end of the front peripheral wall, as shown in FIGS.
As shown in FIG. 7, a single second supply passage hole 80 is formed which is appropriately communicated with the third and fourth supply holes 66b and 67b. Further, as shown in FIGS. 5C to 7C, the above-described discharge holes 69a, 70a, 69b, 70
b, each of which has a single first and second discharge passage hole 8
1, 82 are formed through. That is, each of the discharge passage holes 81 and 82 is formed on the same plane in the radial direction. In addition, the rotary valve 72 is
The second supply passage holes 79 and 80 and the first and second discharge passage holes 8
The peripheral wall portions other than 1 and 82 are provided with supply holes 66 a to 67 b and discharge holes 69 a to 7 depending on the rotation position of the rotary vane 50.
Functions as a shutoff valve for Ob. Since only one supply passage hole 79, 80 and one discharge passage hole 81, 82 are provided on the same plane in the radial direction, the opening area of each hole is rectangular in the circumferential direction. It is set large.

The electromagnetic coil 7 of the step motor unit 71
Reference numeral 4 outputs a control signal (control current) from the control unit 83 which detects the current engine operating state based on various sensors such as a crank angle sensor, an air flow meter, a throttle opening sensor, and a water temperature sensor. It has become.

The operation of the control mechanism 25 will be described below.

First, at the time of low engine speed and low load, a control signal is output from the control unit 83 to the step motor unit 71, and the drive rod 76 rotates a predetermined amount clockwise from the counterclockwise position in FIGS. 5A to 5D. The rotary valve 72 is rotated to the position shown in FIGS. 5A to 5D. As a result, the first and second supply passage holes 79 and 80 temporarily communicate with the first supply holes 66a and 66b, and
The hydraulic pressure is supplied to the upper and lower first hydraulic chambers 51, 51 from above. At the same time, the first and second discharge passage holes 81 and 82 are
As shown in C and D, the hydraulic pressure in the upper and lower second hydraulic chambers 52, 52 communicates with the second discharge holes 70a, 70b, respectively, and passes through the annular groove 68a, the space 68b, and the drain hole, and is on the cylinder head 1. Is discharged. At this time, the second and fourth supply holes 6
7a and 67b are maintained in a closed state by the peripheral wall of the rotary valve 72 as shown in FIGS.
The communication with the two supply passage holes 79 and 80 is shut off.

Therefore, while the internal pressure of the first hydraulic chambers 51, 51 increases, the internal pressure of the second hydraulic chambers 52, 52 decreases, and the rotary vane 50 rotates counterclockwise in the figure and stops at the illustrated position. I do. That is, the rotary valve 72 is configured as shown in FIG.
After that, the first hydraulic chamber 5
As the internal pressure of the first and the first 51 increases, only the rotary vane 50 rotates, and the matching positions of the first and second supply passage holes 79 and 80 and the first and third supply holes 66a and 66b are shifted. ,
The third supply holes 66a and 66b rotate to a position where they are closed by the peripheral wall of the rotary valve 72. In this position,
One side surface of both blade portions 50b, 50b is formed by each partition wall 56, 57.
Are in contact with the one-side tapered surfaces 56a, 57a.

For this reason, the control shaft 18 also rotates in the same direction as the rotary vane 50, and the center of the annular disk 9 is driven by the eccentric cam 21 by the drive shaft 2 (camshaft 3).
Eccentric to the center of As a result, the actual valve lift characteristic of the intake valve is changed with respect to the cam lift characteristic, and the opening timing is delayed, and at the same time, the closing timing is advanced, and the valve operating angle is reduced. That is, in the low engine speed and low load region as described above, the opening timing of the intake valve is slightly delayed and the closing timing is advanced, so that the valve overlap of the intake and exhaust valves is reduced, and the residual gas in the combustion chamber is reduced. Fuel efficiency can be improved by stable combustion. Further, due to the early closing timing, the intake charging efficiency is improved, and the low-speed torque can be increased.

On the other hand, when the engine shifts to a high speed region,
Contrary to the above operation, the drive rod 76 is rotated in the same direction by the control signal from the control unit 83, and the rotary valve 72 is rotated to the position shown in FIG. As a result, the first and second supply passage holes 7
9, 80 are the second and fourth supply holes 67a, 67b temporarily.
From the hydraulic supply passage 65 to the second hydraulic chambers 52, 52.
Is supplied with hydraulic pressure. At the same time, the first and second discharge passage holes 81 and 82 communicate with the first and third discharge holes 69a and 69b as shown in FIGS. 6C and 6D, so that the hydraulic pressure in the first hydraulic chambers 51 and 51 is reduced. 68 and is discharged onto the cylinder head 1. At this time, the first and third supply holes 66a and 66b are
6A and 6B, the closed state is maintained by the peripheral wall portion of the rotary valve 72, and the first and second supply passage holes 7 are provided.
Communication with 9,80 is interrupted.

Therefore, while the internal pressure of the second hydraulic chambers 52, 52 increases, the internal pressure of the first hydraulic chambers 51, 51 decreases, and the rotary vane 50 rotates clockwise in FIG.
It stops at the position shown in FIG. 7D. That is, also in this case, the rotary valve 72 rotates to the position shown in FIG. The second supply passage holes 79, 80 and the second and fourth supply holes 67a, 67b are out of alignment, and the second and fourth supply holes 67a, 67b are eventually formed.
Rotates to a position where it is closed by the peripheral wall of the rotary valve 72 (see FIG. 7). At this position, both wing portions 50b, 5
The other side surface of Ob abuts on the other tapered surfaces 56b and 57b, and further rotation is restricted.

Therefore, the control shaft 18 also rotates in the same direction, and the center of the annular disk 9 coincides with the center of the drive shaft 2 by the cam action of the eccentric cam 21.

Therefore, in this case, there is no rotation phase between the annular disk 9 and the drive shaft 2, and the valve lift characteristic follows the cam lift characteristic. That is, as compared with the low-speed low-load region, the operating angle is increased, the opening timing is advanced, and the closing timing is delayed, so that the intake charging efficiency using the intake inertia is improved, and high output can be achieved.

When the engine shifts from, for example, a low rotation range to a predetermined intermediate operation range, the control unit 83
The rotary valve 72 rotates clockwise from the position shown in FIG. 5 to a predetermined intermediate rotation position via the drive rod 76 in response to a control signal from For this reason, the first and second supply passage holes 79 and 80 temporarily communicate with the second and fourth supply holes 67a and 67b, and at the same time, the first and second discharge passage holes 81 and 80.
82 also communicates with the first and third discharge holes 69a, 69b.
Therefore, while the internal pressure of the second hydraulic chambers 52, 52 increases, the internal pressure of the first hydraulic chambers 51, 51 decreases, and the rotary vane 50 rotates clockwise from the position shown in FIG.
a, 67b, 79, and 80 are out of alignment with each other.
At the same time as the discharge holes 69a and 69b are closed by the peripheral wall of the rotary valve 72, the second and fourth discharge holes 7a and 69b are closed.
0a and 70b are also closed, and the supply and discharge of the hydraulic pressure in the hydraulic chambers 51 and 52 are stopped. At this time, the first and third supply holes 66a and 66b are always closed by the peripheral wall of the rotary valve 72, as described above.

As a result, the control shaft 18 is held at the target rotational position via the rotary vane 50. Therefore, it is possible to control the operating angle of the intake valve to an arbitrary intermediate operating angle. That is, the annular disk 9 can be positioned at an arbitrary eccentric position with respect to the axis of the drive shaft 2 through the control housing 10 in a stepless manner, and the valve timing is steplessly controlled according to a change in the engine operating state. can do.

In addition, the fluctuations in the rotational torque transmitted from the camshaft 3 to the control shaft 18 are transferred to the respective hydraulic chambers 51, 52.
It becomes possible to absorb by the action of the hydraulic damper inside. For this reason, occurrence of a tapping sound, abrasion, or the like during operation between the outer peripheral surface of the eccentric cam 21 fixed to the control shaft 18 and the inner peripheral surface of the cam fitting hole 19 is prevented.

Further, the electromagnetic actuator 47 blocks the transmission of the rotation torque fluctuation and merely drives the rotary valve 72 to rotate, so that the driving load of the step motor unit 71 can be sufficiently reduced. Thus, the overall size of the control mechanism 25 can be reduced.

Further, the opening areas of the supply holes 66a to 67b and the supply passage holes 79 and 80 and the discharge holes 69a to 69b and the discharge passage holes 81 and 82 can be set to be large along the circumferential direction. Each corresponding hole accompanying the rotation of the valve 72, for example, the first and third supply holes 66a, 66
b, supply passage holes 79, 80 and second and fourth discharge holes 70
The time when the discharge passage holes 81 and 82 overlap with the discharge passage holes 81 and 82 is shortened, that is, the speed until the communication is established is increased.
As a result, the movement time of the annular disk 9 in the eccentric direction or the concentric direction with respect to the drive shaft 2 is sufficiently reduced, and the control response is improved. In particular, since the control time on both the supply side and the discharge side of the hydraulic pressure to each of the hydraulic chambers 51, 51, 52, 52 can be shortened, the responsiveness is remarkably improved.

Next, the control shaft 1 which is a main part of the present invention will be described.
The stopper means for restricting the rotation position of 8 will be described. In this embodiment, a projection 91 as shown in FIG. 9 is provided on a part of the outer peripheral surface of the control shaft 18. The projection 91 is formed as a separate member from the control shaft 18 and is firmly fixed to the outer peripheral surface of the control shaft 18 by screws (not shown) or the like. A stopper 92 is provided on the cam bracket 5 so as to abut on the protrusion 91, and the rotation of the control shaft 18 to one side is regulated to a predetermined position by the abutment of the two. The stopper 92 is screwed into a screw hole of a block 93 provided on a side surface of the cam bracket 5, and is fixed by a lock nut 94. Therefore, the stopper 9
2 can be moved forward and backward to adjust its position. Further, by providing the stopper 92 on the cam bracket 5, there is no need to change the mold of the cylinder head 1 itself.

When the projection 91 is in contact with the stopper 92, the hydraulic actuator 46 is located at a position near the state shown in FIG. 5, and the amount of eccentricity of the annular disk 9 with respect to the center of the drive shaft 2 is largest. Has become. In other words, the characteristics of the valve operating angle suitable for idling are the smallest. In this eccentric state, the valve spring reaction force acts on the eccentric cam 21 to rotate the control shaft 18. However, the rotation force due to the valve spring reaction force is reduced by the protrusion 91 and the stopper 92. And act in the direction of pressing each other.

According to the configuration of this embodiment, the control mechanism 25
Even if a failure occurs, the rotational position of the control shaft 18 is maintained at the expected rotational position, and the valve operating angle does not become excessively narrow. Accordingly, occurrence of abnormal valve movement can be prevented. In addition, even at the time of starting the engine in which the hydraulic pressure introduced into the hydraulic actuator 46 is very low, the rotational position of the control shaft 18 is maintained at a desired position, and a predetermined valve lift characteristic can be reliably ensured. Therefore,
The start can be stably performed, and the idling operation immediately after the start can be stabilized. In particular, since the stopper means directly positions the control shaft 18 itself, the accuracy is much higher than when the position is regulated by the control mechanism 25 side. That is, at the connection between the control mechanism 25 and the control shaft 18,
As shown in an enlarged manner in FIG. 8, there is always a small gap S between the fitting surfaces formed of two parallel planes, so that a play at a small angle θ occurs. Therefore, even if the rotation position is regulated on the hydraulic actuator 46 side, the accuracy is reduced by the play. However, by regulating the rotation of the control shaft 18 itself, the influence of the play can be eliminated, Constant valve lift characteristics can always be secured.

Further, since the control shaft 18 is directly positioned with high precision as described above, it is possible to perform so-called learning control at the regulated position. In addition,
In this case, a control shaft rotation position detecting means for detecting the rotation position of the control shaft 18 is necessary. For example, a rotation angle sensor such as a rotary encoder is provided at an end of the control shaft 18 opposite to the control mechanism 25. . FIG.
Shows a flowchart of this learning control. In step (denoted by S in the figure) 1, the engine speed,
Read engine operating conditions such as load and oil temperature, and
Therefore, the control mechanism 25 sets the rotational position corresponding to this as a target.
Drives the control shaft 18 to rotate. Then, in step 3, the actual rotation position is detected by the rotation angle sensor. This position detection is performed using the previously learned regulation position as a reference point (for example, 0 point). In step 4, the detected position is compared with the target position, and the processes in steps 1 to 4 are repeated so that they match. In step 5, it is determined whether or not the rotation of the control shaft 18 is in a condition mechanically restricted by the stopper means described above.
In step 6, the actual position of the control shaft 18 in the forcibly regulated state is detected by the rotation angle sensor, and this is learned as a subsequent reference point. This makes it possible to easily absorb individual differences in the mounting accuracy of the control mechanism 25 and changes over time.

For the above learning control, it is possible to restrict the rotational position of the control shaft 18 at the rotational position at which the valve operating angle is maximized. At idle when conditions are easy to continue,
Alternatively, in order to perform learning immediately after the engine is started, it is preferable to regulate the valve at a position where the valve operating angle is minimized as in the above-described embodiment.

FIG. 11 shows an example in which stopper means are provided in two directions. That is, the stopper 92 described above is provided at a position where the valve operating angle is minimized, and
A second stopper 95 is provided at a position where the valve operation angle is maximized. The stopper 95 is also made of a bolt that can move forward and backward, and is fixed by a lock nut 96.

By the way, as described above, the control shaft 18
If the rotation of the control shaft 18 is forcibly restricted by the stopper means, the control mechanism 18 continues to be driven by the control mechanism 25 even in the state where the position is restricted, and there is a possibility that the control shaft 18 may be twisted or an unnecessary load on the hydraulic actuator 46 may occur. This problem can be avoided by controlling the rotational position to be restricted to the position by holding the control mechanism 25 at the position immediately before the rotational position so that the driving force by the hydraulic actuator 46 does not act on the stopper means. Can be.

FIG. 12 is a flowchart showing this control. In step 1, the engine operating condition at that time is a reference position condition for setting the control shaft 18 as a reference position (a position regulated by the stopper means). It is determined whether or not. If the operating conditions are other than these conditions, step 2
Then, the process proceeds to step 3, where the control mechanism 25 controls the target rotational position set in accordance with the operating conditions. That is, normal control is performed. On the other hand, if it is the reference position condition in step 1, the process proceeds to step 4 to detect the actual rotational position of the control shaft 18, and proceeds to step 5 to correct the initial position. Specifically, the projection 91 is rotated by the control mechanism 25 in a direction in which the projection 91 is slightly separated from the stopper 92, and the position is maintained.

Thus, the driving force of the hydraulic actuator 46 does not act on the projection 91 and the stopper 92. And when starting or idling when the hydraulic pressure is not enough,
Only when the control shaft 18 tries to rotate due to the valve spring reaction force, the projection 91 actually collides with the stopper 92. Therefore, it is possible to suppress the abrasion of the protrusion 91 and the stopper 92 over time and the torsion of the control shaft 18. Note that the above-described control is preferably performed after starting, learning is performed at a forcibly restricted position, and is started after the learning is completed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line EE in FIG. 1;

FIG. 3 is a vertical sectional view of a control mechanism in the embodiment.

FIG. 4 is an exploded perspective view of the control mechanism.

FIG. 5 shows a state of the hydraulic actuator when the annular disk of the present embodiment is at an eccentric position, where A is AA in FIG. 3;
B is a cross-sectional view taken along the line BB of FIG.
C is a sectional view taken along line C, and D is a sectional view taken along line DD in FIG.

6 shows a state in which the rotary valve is rotated in the other direction to move the annular disk from the eccentric state to the concentric position, wherein A is a sectional view taken along line AA of FIG. 3, and B is BB of FIG.
C is a cross-sectional view taken along the line CC of FIG.
It is a D line sectional view.

7 shows a state of the hydraulic actuator when the annular disk is at a concentric position, where A is a cross-sectional view taken along the line AA in FIG. 3,
B is a cross-sectional view taken along the line BB in the same figure, C is a cross-sectional view taken along the line CC in the same figure, and D is a cross-sectional view taken along the line DD in the same figure.

FIG. 8 is a sectional view of a connecting portion between the control shaft and the hydraulic actuator.

FIG. 9 is a sectional view showing a configuration of a stopper portion.

FIG. 10 is a flowchart showing a flow of a learning control process.

FIG. 11 is a sectional view showing an embodiment in which stopper means are provided at both the minimum position and the maximum position of the valve operating angle.

FIG. 12 is a flowchart showing control to maintain the position immediately before the restriction position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Drive shaft 3 ... Cam shaft 4 ... 1st flange part 5 ... Cam bracket 8 ... 2nd flange part 9 ... Annular disk 10 ... Control housing 18 ... Control shaft 21 ... Eccentric cam 22 ... Eccentric bush 25 ... Control mechanism 46 ... Hydraulic actuator 47 ... Electromagnetic actuator 91 ... Protrusion 92 ... Stopper

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Hidaka 1370 Onna, Atsugi-shi, Kanagawa Inside Unisia Gex Co., Ltd. (56) References JP-A-7-42515 (JP, A) JP-A-4-325706 (JP, a) JP flat 7-91302 (JP, a) JP flat 7-269406 (JP, a) JP Akira 61-237864 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ F01L 13/00 301 F02D 13/02 F16C 3/28

Claims (4)

(57) [Claims] 1. A drive shaft disposed over a plurality of cylinders and rotating in synchronization with rotation of an engine; a drive shaft fitted to the outer periphery of the drive shaft so as to be relatively rotatable; and divided for each cylinder. A cylindrical camshaft having a plurality of cams each driving an intake / exhaust valve on the outer periphery thereof; a first flange portion provided in a flange shape at an end of each camshaft; A second flange portion provided on the drive shaft side so as to oppose the respective portions; an annular disk disposed between the two flange portions; and a mutual disk between the annular disk and the two flange portions. A pair of radially extending engagement grooves for transmitting rotational movement while allowing eccentricity, and a pair of pins engaging with the engagement grooves, and a ring-shaped disk, which rotatably holds the annular disk. Cam fitting hole and bush A control housing fitting hole is opened and formed, together with the inner circumferential surface rotatably fitted to the outer periphery of the stationary shaft, the outer peripheral surface is rotatably fitted in the bush fitting hole of the control housing, said control An eccentric bush that movably supports the housing along a direction perpendicular to the axis; and an eccentric cam rotatably fitted in a cam fitting hole of the control housing. The rotation causes the control housing to move along the direction perpendicular to the axis. A control shaft for moving the control shaft, and an actuator for driving the shaft to rotate so as to change the rotational position of the control shaft. by regulating the comprises a stopper means for performing position regulation in the rotation position of the control shaft the valve operating angle is minimized, upper Stopper means is provided on the control shaft periphery
Projection and a cylinder head so as to abut the projection.
Stopper Toka Rannahli provided on the cam bracket of the above,
And, the above control shaft due to the valve spring reaction force
Rotational force presses the protrusion and stopper against each other
Intake and exhaust valve drive control device for an internal combustion engine, characterized by being configured to act on that direction. 2. The internal combustion engine according to claim 1, further comprising control shaft rotation position detection means for detecting the rotation position of the control shaft, and learning the control shaft rotation position when the control shaft position is regulated. Engine intake and exhaust valve drive control device. 3. The internal combustion engine according to claim 1, wherein said actuator is held at a position immediately before the rotation position to be regulated by said stopper means, so that a driving force by said actuator does not act on said stopper means. Engine intake and exhaust valve drive control device. Wherein the intake and exhaust valves drive control apparatus for an internal combustion engine according to claim 1, wherein said stopper is adjustable in position.