JPH0734820A - Intake/exhaust valve drive control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To provide the valve lift characteristic suitable for the operating condition, prevent the abrasion between the pin and the engaging groove, and secure the starting quality. CONSTITUTION:A cylindrical cam shaft 22 is arranged on the outer circumference of a driving shaft 21 which is synchronously rotated with the engine, and an annular disk 29 is arranged between a flange part 27 of the cam shaft 22 and a flange part 32 of a sleeve 28 connected to the driving shaft 21. The annular disk 29 is held by a swayable control ring 35, and a pair of pins 36, 37 engaged with engaging grooves 30, 33 of the flange parts 27, 32 are mounted in a rotatable manner. The annular disk 29 is sway-controlled by the driving mechanism mainly according to the engine speed, and can be selectively switched to the position where the concentric condition with the cam shaft 22 or the like is kept on the high speed side, while to the position where the eccentric condition is kept on the low speed side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve drive control device for variably controlling the opening / closing timing and operating angle of an intake valve / exhaust valve according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, various types of devices for variably controlling the opening / closing timings and operating angles of intake / exhaust valves have been provided. One of them is, for example, Japanese Utility Model Publication 57-198.
Some are disclosed in Japanese Patent No. 306.

FIG. 9 and FIG. 10 show this conventional intake / exhaust valve drive control device. The outline thereof will be described. In the drawings, reference numeral 2 is rotatably provided on the outer periphery of a drive shaft 1, and an intake valve is shown. 16 is a cam for opening the valve 16 against the spring force of the valve spring 17, and the cylindrical cam 2 includes a cam bearing bracket 3 and a flange portion 5 fixed to the drive shaft 1 via a key 4. The axial positioning is performed by.
Further, the flange portion 7 having the engagement groove 6 on one side portion of the cam 2
On the other hand, the engaging groove 8 is formed in the flange portion 5 as well.
Is formed, and an annular disk 9 is interposed between the flange portions 5 and 7. The disk 9 has pins 10 and 11 which engage with the engaging grooves 6 and 8 at opposite positions on both sides.
Is provided, and the outer periphery is rotatably held by the control ring 12. This control ring 12 has a protrusion 1 on the outer circumference.
A gear portion 12b, which is swingably supported by a support hole 13 on the cylinder head side via 2a, is located on the opposite side of the projection 12a meshes with a gear ring 14a on the outer circumference of the rocker shaft 14.

The control ring 12 is a gear ring 14a.
A drive mechanism (not shown) swings in one or the other direction via the gear portion 12b according to the engine operating state. That is, when the center C of the disk 9 is at the position shown in FIG. 9, the rotation centers of the drive shaft 1 and the disk 9 coincide with each other, so that the disk 9 is driven by the drive shaft 1 via the pin 11 and the engaging groove 8. The cam 2 is synchronously rotated at a constant speed, and the cam 2 is synchronously rotated at a constant speed with the disk 9 through the pin 10 and the engaging groove 6.

Further, a rocker shaft 1 which supports a rocker arm 15 by a drive mechanism in accordance with a change in engine operating state.
When 4 is rotated, the control ring 12 swings around the projection 12a as a fulcrum, whereby the center C of the disk 9 is moved to the drive shaft 1
Eccentric to the center of. In this state, the disk 9 having the engaging grooves 6 and 8 and the pins 10 and 11 constitute a kind of eccentric shaft coupling, and the cam 2 rotates following the drive shaft 1, but the rotational speeds of both are not constant. It becomes constant speed. That is,
During one rotation of the drive shaft 1, the rotation phase of the disc 9 changes with respect to the drive shaft 1, and at the same time, the rotation phase of the cam 2 also changes with respect to the disc 9. Therefore, the cam 2 causes a phase difference with respect to the drive shaft 1 as indicated by the broken line or the alternate long and short dash line in FIG. 11A, and as a result, as shown in FIG. 11B, the valve lift characteristic indicated by the solid line. Can be changed like a broken line or an alternate long and short dash line.

[0006]

However, in the above-mentioned conventional apparatus, the period between the broken line and the alternate long and short dash line in FIG. 11 is continuously changed according to the engine operating condition. The concentric state period in which the centers of the three persons are coincident with each other as in 9 is practically almost nonexistent during the operation, and the pins 10, 11 and the engaging grooves 6,
8 and slippage will occur. Therefore, the facing inner surfaces 6a to 8b of the pins 10 and 11 and the engagement grooves 6 and 8 are easily worn, and a relatively large gap is generated between the pins 6, 8 and 10 with the passage of time. As a result, there is a possibility that a tapping sound may be generated due to the positive and negative rotational torque fluctuations of the camshaft 1 or a valve timing deviation may occur, resulting in deterioration of control accuracy.

[0007]

SUMMARY OF THE INVENTION The present invention is a cam having a drive shaft that rotates in synchronization with the rotation of an engine and a cam that is arranged coaxially with the drive shaft and that drives an intake / exhaust valve on the outer periphery. A shaft, a flange portion provided at an end portion of the cam shaft and having an engagement groove formed along the radial direction, and a flange portion provided on the drive shaft side so as to face the flange portion and in the radial direction. A flange portion along which an engaging groove is formed, a swingable annular disc disposed between the both flange portions, and both side portions of the annular disc are provided so as to project in opposite directions to each other. An intake / exhaust valve drive control device comprising: a pin that engages in each engagement groove of a flange portion; and a drive mechanism that swings the annular disc in accordance with an engine operating state. First control position that is approximately concentric with the axis It is characterized in that alternatively switching control in a second control position by a predetermined eccentricity.

Particularly, in the invention of claim 2, the engine is controlled to the first control position on the high speed side and to the second control position on the low speed side.

Further, the invention of claim 3 is characterized in that the drive mechanism is a hydraulic drive mechanism, and is in a first control position when hydraulic pressure is supplied and in a second control position when hydraulic pressure is released.

Further, according to the invention of claim 4, in order to suppress wear, the pin is rotatably fitted and supported in the holding hole of the annular disk, and is in surface contact with the inner surface of the engaging groove. In addition, a flat portion was formed on the protruding portion of the pin.

According to a fifth aspect of the present invention, the step portion formed between the cylindrical surface of the pin and the flat surface portion is brought into contact with one flange surface, and the base end surface of the pin penetrating the holding hole is the other. The pin was axially positioned by making contact with the flange surface.

[0012]

In the first control position in which the center of the annular disc is aligned with the center of the drive shaft, the camshaft rotates at a constant speed in synchronization with the drive shaft via the annular disc or the like, that is, without phase difference. . In this state, the pin and the engagement groove do not substantially slip.

On the other hand, in the second control position in which the annular disc is swung in one direction by the drive mechanism, the center of the annular disc is eccentric from the center of the drive shaft, so that the drive shaft and the cam shaft work together at an unequal speed. As a result, a phase difference occurs during rotation. Therefore, the sliding positions of the engagement groove of the flange portion on the drive shaft side and the pin on one side, and the engagement groove of the flange portion on the cam shaft side and the pin on the other side move for each rotation of the drive shaft. As a result, the valve timing and its operating angle change. At the second control position, each pin transmits the rotational force while sliding on the engagement groove.

In the present invention, since the first control position and the second control position are selectively switched and controlled, the slip between the pin and the engagement groove is eliminated during a considerable period of the operating time, and the wear thereof is eliminated. Is suppressed. In particular, by setting the first control position on the engine high speed side where the rotation speed is high, it is further advantageous in suppressing wear.

Further, by setting the second control position suitable for the low speed side when the hydraulic pressure of the drive mechanism is released, the valve suitable for the low speed side is provided in the unlikely event of a failure of the hydraulic system or a start of insufficient hydraulic pressure. It has lift characteristics and does not cause deterioration of drivability and startability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an intake / exhaust valve drive control device according to the present invention will be described below with reference to FIGS. In the figure, 21 is a drive shaft to which rotational force is transmitted from an engine crankshaft (not shown) through a sprocket, 22 is arranged on the outer periphery of the drive shaft 21 with a certain gap, and is coaxial with the center X of the drive shaft 21. It is a hollow cylindrical camshaft provided above. The drive shaft 21 extends in the front-rear direction of the engine and has a hollow shape. The camshaft 22 is divided into cylinders.

The cam shaft 22 is rotatably supported by a cam bearing at the upper end of a cylinder head (not shown), and as shown in FIG. 2, an intake valve 23 and a valve spring 24 are provided at predetermined positions on the outer circumference. A plurality of cams 26 ... Which are opened against the spring force via the valve lifter 25 are integrally provided. The cam shaft 22 is divided into a plurality of pieces as described above, and the flange portion 27 is provided at one of the divided ends. Also,
A sleeve 28 and an annular disk 29 are arranged between the ends of the camshaft 22 divided into a plurality of parts. As shown in FIG. 4, the flange portion 27 is formed with an elongated rectangular engaging groove 30 extending in the radial direction from the hollow portion, and has a flange surface 27a that slidably contacts one surface of the annular disc 29. have.

The sleeve 28 has a small-diameter one end rotatably inserted into the other split end of the camshaft 22, and is fitted to the outer periphery of the drive shaft 21 and is diametrically pierced. It is fixedly connected to the drive shaft 21 via a pin 31. Further, the flange portion 32 provided on the other end portion of the sleeve 28 is positioned so as to face the flange portion 27 on the camshaft 22 side, and as shown in FIG.
An elongated rectangular engagement groove 33 is formed along the radial direction, and a flange surface 28a that slidably contacts the other surface of the annular disk 29 is formed on the outer peripheral surface. The engagement groove 33 is the engagement groove 3 of the flange portion 27 on the camshaft 22 side.
It is arranged on the opposite side, which is different from 0 by 180 °.

The annular disc 29 has a substantially toroidal plate shape, an inner diameter of which is substantially the same as the inner diameter of the cam shaft 22, and an annular gap S is formed between the annular disc 29 and the outer peripheral surface of the drive shaft 21. In addition, the outer peripheral portion 29a having a small width is rotatably held on the inner peripheral surface of the control ring 35 via the annular bearing metal 34. Further, the holding holes 29b and 29c are respectively provided at the facing positions on the diameter lines different from each other by 180 °.
Are formed through the holding holes 29b and 29c,
A pair of pins 36 and 37 that engage with the respective engagement grooves 30 and 33 are fitted and arranged. The pins 36 and 37 project in opposite directions to each other in the axial direction of the camshaft, and the base portion formed of a cylindrical surface is rotatably fitted and supported in the holding holes 29b and 29c, and also from the surface of the annular disc 29. As shown in FIG. 4 and FIG. 5, the projecting tip portion has opposing inner surfaces 30a, 30b, 33a, 33b of the engaging grooves 30, 33.
A flat portion 36a, 36b, 37a having a width across flats that abuts
37b is formed. In addition, the positioning of the pins 36 and 37 in the axial direction is performed by the pin 3 in the protruding direction.
6, 37 cylindrical surfaces and the flat surface portions 36a, 36b, 37
The contact between the stepped portions 36c, 37c and the flange surfaces 27a, 28a generated between the pins 3a, 37b, and the retreating direction causes the pin 3 penetrating the holding holes 29b, 29c.
6, 37 base end surfaces 36d, 37d and flange surface 28a,
It is carried out by the contact with 27a.

The control ring 35 has a substantially annular shape, and as shown in FIG. 2, has a boss portion 35a on a part of its outer periphery, and a swing shaft 38 penetrating the boss portion 35a is used as a fulcrum. It is configured to be vertically swingable along a plane orthogonal to the axial direction of the drive shaft 21. A lever portion 35b is provided on the outer peripheral surface opposite to the boss portion 35a so as to project in the radial direction, and the swinging position is controlled by the drive mechanism 39 via the lever portion 35b.

As shown in FIGS. 2 and 6, the drive mechanism 39 includes first and second cylinders 40 and 41 formed at predetermined portions of the cylinder head so as to face each other, and inside the cylinders 40 and 41. It includes a hydraulic piston 42 and a retainer 43 that are fitted into each other in a retractable manner, and a hydraulic circuit 44 that advances and retracts the hydraulic piston 42 by supplying and discharging hydraulic pressure to and from the hydraulic chamber 40a defined in the first cylinder 40. The hydraulic piston 42 and the retainer 43 are opposed to each other and hold the arcuate tip end portion of the lever portion 35b in the vertical direction between the tip ends of the two.

The retainer 43 provided in the second cylinder 41 is formed in a substantially cylindrical shape with a bottom, and the second cylinder 4
The spring force of the coil spring 45 arranged in the first unit 1 urges the coil spring 45 in the protruding direction. Further, the retracted position of the retainer 43 is regulated by the stopper portion 41b, and at the maximum retracted position in contact with the stopper portion 41b, that is, the maximum projected position of the hydraulic piston 42, the rotation center of the annular disc 29 is rotated. Y and the center X of the drive shaft 21 are set to be concentric. Incidentally, reference numeral 4 in FIG.
1c shows an air vent hole.

The hydraulic circuit 44 has an oil passage 47, one end of which communicates with the oil pan 46 of the engine and the other end of which communicates with the hydraulic chamber 40a, and an oil provided on the oil pan 46 side of the oil passage 47. A pump 48 and a 3-port 2-position electromagnetic switching valve 49 provided on the downstream side of the oil pump 48.
It is mainly composed of and. The hydraulic circuit 44
Is generally configured using an engine lubrication system, and the oil pump 48 and the like are shared with the engine lubrication system. The electromagnetic switching valve 49 is switching-controlled by the controller 50 based on operating condition signals such as the engine speed and the intake air amount. Specifically, the ON / OFF switching of the electromagnetic switching valve 49 is performed in accordance with the characteristics as shown in FIG. 8. The low speed area A is OFF and the high speed area B is. Is turned on and controlled respectively. When the electromagnetic switching valve 49 is turned on, the oil passage 47 communicates with the hydraulic chamber 40a to supply hydraulic pressure, and when turned off, the oil passage 4 is opened.
7 The downstream portion and the drain passage 51 communicate with each other to release the hydraulic pressure. Incidentally, when the engine is stopped, the electromagnetic switching valve 49 is kept in the OFF state.

Next, the operation of the embodiment configured as described above will be described.

First, in the region B on the high speed side, as described above, the controller 50 outputs the ON signal to the electromagnetic switching valve 49. As a result, the hydraulic oil pressure-fed from the oil pump 48 to the oil passage 47 is directly supplied to the hydraulic chamber 40a. Therefore, as the internal pressure of the hydraulic chamber 40a rises, the hydraulic piston 42 pushes the lever portion 35b down to the limit position against the spring force of the coil spring 45 as shown by the solid lines in FIGS. The rotation center Y of the annular disk 29 and the center X of the drive shaft 21 coincide with each other. In this case, a rotational phase difference does not occur between the annular disc 29 and the drive shaft 21, and the center of the camshaft 22 and the center Y of the annular disc 29 also coincide with each other.
The rotation phase difference between 9 does not occur either. Therefore, the drive shaft 21,
The annular disc 29 and the camshaft 22 are rotated at a constant speed synchronously via the pins 36 and 37. As a result,
The valve lift characteristic as shown by the solid line in FIG. 7A is obtained. Further, at this time, substantially no slip occurs between the pins 36 and 37 and the engagement grooves 30 and 33.

On the other hand, in the area A on the low speed side, the controller 50 outputs an OFF signal to the electromagnetic switching valve 49. As a result, the upstream side of the oil passage 47 is shut off, and the downstream side of the oil passage 47 and the drain passage 51 are connected. Therefore, the hydraulic pressure in the hydraulic chamber 40a is released, and the hydraulic piston 42 moves the valve spring 24 and the coil spring 45.
It retreats with the spring force of. Therefore, the control ring 35 is pushed up by the retainer 43 as shown by the alternate long and short dash line in FIGS. 2 and 6, and swings upward with the swing shaft 38 as a fulcrum so that the center Y of the annular disk 29 is driven by the drive shaft. It is eccentric from the center X of 21. In this state, the engagement groove 33 of the sleeve 28
The sliding position of the pin 37, the engagement groove 30 of the camshaft 22, and the pin 36 moves for each rotation of the drive shaft 21, and the rotation speed of the annular disk 29 becomes unequal rotation.

In particular, in the angular region where the sliding position of the one locking groove 33 and the pin 37 approaches the center X of the drive shaft 21, the sliding position of the other locking groove 30 and the pin 36 moves away from the center X. Get involved. In this case, the annular disc 29 has a small angular velocity with respect to the drive shaft 21, and further the angular velocity of the camshaft 22 with respect to the annular disc 29 also becomes small.
Therefore, the angular velocity of the camshaft 22 is determined by the drive shaft 21.
It is in a state of being decelerated double. On the contrary, in the angular region where the sliding position of the one locking groove 33 and the pin 37 is separated from the center X of the drive shaft 21, the other locking groove 30 and the pin 36 are provided.
The sliding position of is close to the center X. In this case, the annular disc 29 has a large angular velocity with respect to the drive shaft 21, and the camshaft 22 also has a large angular velocity with respect to the annular disc 29. Therefore, the angular velocity of the camshaft 22 is doubled with respect to the drive shaft 21.

As a result, a relatively large phase difference is provided between the drive shaft 21 and the cam shaft 22, as shown by the alternate long and short dash line in FIG. 7 (B). Further, the same phase point (point P) exists in the middle of the maximum and minimum points of the rotational phase difference. still,
In the characteristic diagram of FIG. 7B, the phase difference in the direction in which the camshaft 22 relatively advances is positive, and the phase difference in the direction in which it is relatively delayed is negative. Then, a region in which the camshaft 22 is relatively behind (regions before the point P1 and P2 to P3
The valve opening timing of the intake valve 23 located in the area (1) is delayed due to the phase difference. On the contrary, the camshaft 22
The valve closing timing of the intake valve 23 located in the region (P1 to P2) on the relatively advanced side advances with the phase difference. Therefore, the valve lift characteristic as shown by the alternate long and short dash line in FIG. 7A is obtained, and the operating angle is reduced.

As described above, the characteristics such as the one-dot chain line are provided in the low speed region A, so that the charging efficiency in the low speed region is improved and the low speed torque is increased. Moreover, since the valve opening timing is delayed, the valve overlap is reduced, the fuel efficiency at idle is improved, and the idle stability is improved.

On the contrary, in the region B on the high speed side, since the operating angle is relatively large and the valve closing timing is late, the charging efficiency in the high speed region is improved. Moreover, the exhaust efficiency is improved by increasing the valve overlap, which improves the torque and output in the high speed range.

In the above structure, the eccentric state of the area A and the concentric state of the area B are selectively switched,
It is possible to secure a large proportion of the period in which no slip occurs between the pins 36 and 37 and the engagement grooves 30 and 33, and to suppress the wear.

Moreover, the pins 36 and 37 are rotatable, and both side edges of the pins 36 and 37 are flat portions 36a, 36b and 37.
Since it is formed in a and 37b, each locking groove 30, 33
The abutting inner surfaces 30a, 30b, 33a, 33b always come into contact with each other in a surface contact state, and wear with time is further suppressed.

Further, in the above embodiment, the pins 36 and 37 and the engagement grooves 30 and 33 are in a concentric state in a high speed region, which is disadvantageous in terms of wear, and their sliding contact is avoided, so that wear is more effective. Suppressed to.

Further, in the above embodiment, when the hydraulic pressure is supplied to the hydraulic chamber 40a, the concentric state is established, and when the hydraulic pressure is released, the eccentric state, that is, the low speed valve lift characteristic is obtained. Therefore, even when the engine generated when the oil pressure generated by the oil pump 48 does not become sufficiently high, it is possible to reliably maintain the low speed valve lift characteristic, and it is possible to obtain good startability and drivability immediately after the start. Moreover, even if the hydraulic pressure cannot be supplied due to a failure of the hydraulic system, the valve lift characteristic for low speed is fixed, so that the engine can be sufficiently operated.

The present invention is not limited to the configuration of the above embodiment, but can be applied to the exhaust valve side or both the intake valve and the exhaust valve.

[0036]

As is clear from the above description, according to the intake / exhaust valve drive control device for an internal combustion engine according to the present invention, the operating periods in which there is no slip between the pins transmitting the rotational force and the engagement groove are compared. It can be ensured at a relatively large rate, and wear between the pin and the engagement groove can be suppressed.

Further, if the hydraulic pressure is supplied to the concentric state on the high speed side, it is possible to prevent wear acceleration at the high speed and to surely provide the low speed valve lift characteristic at the time of starting with low hydraulic pressure. Is improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway view showing a main part of an embodiment of the present invention.

FIG. 2 is a view on arrow A in FIG.

FIG. 3 is a plan view showing a main part of this embodiment.

FIG. 4 is a sectional view taken along line BB of FIG.

5 is a cross-sectional view taken along line CC of FIG.

FIG. 6 is a schematic diagram showing the configuration of a drive mechanism.

FIG. 7 is a characteristic diagram showing a characteristic of a rotational phase difference between a drive shaft and a cam shaft and a valve lift characteristic for comparison.

FIG. 8 is a characteristic diagram showing a region of switching control for engine operating conditions.

FIG. 9 is a sectional view of a conventional intake / exhaust valve drive control device.

10 is a cross-sectional view taken along the line DD of FIG.

FIG. 11 is a characteristic diagram showing a rotational phase difference characteristic and a valve lift characteristic of a conventional intake / exhaust valve drive control device.

[Explanation of symbols]

 21 ... Drive shaft 22 ... Cam shaft 27 ... Flange part 32 ... Flange part 29 ... Annular disk 30, 33 ... Engagement groove 36, 37 ... Pin 36a, 36b, 37a, 37b ... Plane part 39 ... Drive mechanism.

Claims (5)

[Claims] 1. A drive shaft that rotates in synchronism with the rotation of an engine, a cam shaft that is arranged coaxially with the drive shaft, and has a cam that drives an intake and exhaust valve on the outer periphery, and an end of the cam shaft. And a flange portion provided on the drive shaft side so as to face the flange portion, and an engagement groove formed along the radial direction. A flange portion, a swingable annular disc disposed between the flange portions, and projecting in opposite directions to both side portions of the annular disc, in the engagement grooves of the flange portions. An intake / exhaust valve drive control device comprising: a pin that engages with each other; and a drive mechanism that swings the annular disc in accordance with an engine operating state, wherein the annular disc has a first control substantially concentric with the drive shaft. Position and a certain amount of eccentricity Intake and exhaust valve drive control device for an internal combustion engine characterized by alternatively be switching control in a control position. 2. The intake / exhaust valve drive control device for an internal combustion engine according to claim 1, wherein the high speed side of the engine is controlled to a first control position and the low speed side is controlled to a second control position. 3. The intake / exhaust system for an internal combustion engine according to claim 2, wherein the drive mechanism is a hydraulic drive mechanism, and is in a first control position when hydraulic pressure is supplied and in a second control position when hydraulic pressure is released. Valve drive controller. 4. The pin is rotatably fitted and supported in a holding hole of an annular disk, and a flat portion is formed on a protruding portion of the pin so as to come into surface contact with an inner surface of the engaging groove. The intake / exhaust valve drive control device for an internal combustion engine according to any one of claims 1 to 3. 5. A step portion formed between the cylindrical surface of the pin and the flat surface portion is brought into contact with one flange surface, and
5. The intake / exhaust valve drive control device for an internal combustion engine according to claim 4, wherein a base end surface of the pin passing through the holding hole is brought into contact with the other flange surface to position the pin in the axial direction.