JPH0734829A - Intake/exhaust valve drive control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the precision in controlling the valve timing by increasing the angular velocity of a cam shaft to further increase the ratio of change of the working angle of a valve. CONSTITUTION:A disk housing is provided in a swayable manner between a second flange part of a driving shaft 21 and a first flange part of a cam shaft through a driving mechanism, and the angular velocity of the cam shaft is changed by the eccentric movement of the center from the axial center (X) of the driving shaft 21 through a pin 36 and an engaging groove 30 as the disk housing is swayed. Each engaging groove 30 is formed in an inclined manner not in the radial direction of each flange part 27, but forward in the rotational direction.

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 of intake / exhaust valves according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Various conventional devices of this kind have been provided, and one of them is described in Japanese Patent Application No. 4-11591 previously filed by the present applicant.

The outline will be described with reference to FIGS. 13 to 15. This intake / exhaust valve drive control device has a hollow drive shaft 1 to which a rotational force is transmitted from a crankshaft of a multi-cylinder engine via a sprocket. A camshaft 2 is provided coaxially with the outer periphery of the drive shaft 1 so as to be relatively rotatable, and a control mechanism 3 is provided between divided ends of the camshaft 2 divided for each cylinder. .

The drive shaft 1 extends along the longitudinal direction of the engine, and a first journal (not shown) on the sprocket side is rotatably supported by a cam bearing provided at the upper end of the cylinder head 7.

Each of the camshafts 2 has two intake valves 4 and 4 per cylinder on the outer periphery thereof and valve lifters 4a and 4 respectively.
It has two cams 6 and 6 which are opened against the spring force of the valve spring 5 via a, and is rotatably supported by a pair of cam bearings 8 and 9 on the cylinder head 7. Has been done.

As shown in FIGS. 13 to 15, the control mechanism 3 has an annular first flange portion 10 integrally provided at one end portion of each camshaft 2 and a predetermined outer peripheral position of the drive shaft 1. An annular second flange portion 13 which is fixed by a connecting pin 11 via a sleeve 12 and faces the first flange portion 10, and an axial center of the drive shaft 1 which is interposed between the flange portions 10 and 13. It is rotatably held via a plain bearing 15 in a substantially annular disc housing 14 provided so as to be swingable in a substantially radial direction from X and a large diameter support hole 14a provided in the inner periphery of the disc housing 14. And an annular disc 16 having a circular shape. The disc housing 14 has one end in the diametrical direction rotatably supported by a support shaft (not shown) fixed to the upper end of the cylinder head 7, and the other end pivoted by a drive mechanism. It has become. Further, the first and second flange portions 1
Elongated engaging grooves 17 and 18 are formed in the outer peripheral portions of 0 and 13 at positions of 180 ° with respect to each other in the radial direction. On the other hand, on both side surfaces of the disk 16, pins 19 and 20 projecting in opposite directions and engaging with the engaging grooves 17 and 18, respectively.
Is projected.

Then, for example, when the engine rotates at high speed, the disk housing 14 does not swing and the center of the disk 16 coincides with the axis X of the drive shaft 1. On the other hand, when the engine rotates at low speed, a drive mechanism (not shown) is used. As a result, the disc housing 14 swings, and the disc 16 is eccentrically moved with respect to the axis X of the drive shaft 1.

That is, for example, at the time of high engine speed rotation, the center of the disk 16 coincides with the axis X of the drive shaft 1 and the rotational phase difference between the drive shaft 1 and the camshaft 2 does not occur. Therefore, as the drive shaft 1 rotates, the cam shaft 2 rotates synchronously with the drive shaft 1 via the control mechanism 3, and the operating angle of the valve by the cams 6 and 6 increases as shown by the solid line in FIG. Since the valve closing timing is delayed as the timing is advanced, the intake charging efficiency using the intake inertial force is improved.

On the other hand, in the low rotation range, the center of the disk 16 is controlled by the drive mechanism via the disk housing 14 so as to be eccentric from the axis X of the drive shaft 1.
When the pins 9 and 20 slide in the radial direction along the inner peripheral surfaces of the engagement grooves 17 and 18, and the pin 20 on one side approaches the axis X of the drive shaft 1, the pin 19 on the other side has an axis center. It becomes a relationship away from X. Therefore, in this case, the disc 16 has a large angular velocity with respect to the drive shaft 1, and
The angular velocity of the camshaft 2 also increases. Therefore, the camshaft 2 is in a state in which the speed is doubled with respect to the drive shaft 1. Therefore, the rotational phase difference between the drive shaft 1 and the camshaft 2 changes as shown in FIG.
When the angular velocity of is relatively large, the rotational phase with respect to the drive shaft 1 advances until both 1 and 2 become uniform velocity, and when the angular velocity of the camshaft 2 becomes relatively small, the rotational phase becomes Delay until the speed becomes constant. And in FIG.
As shown by A, the in-phase point P exists in the middle of the maximum and minimum points of the rotational phase difference, and in the change of the rotational phase of FIG. A, the operating angle of the valve is from point P as shown by the broken line in FIG. 16B. Also, the valve opening timing before is delayed, the valve closing timing after point P is advanced, and the overall control is made small. Therefore, the valve overlap of the intake and exhaust valves is reduced, the residual gas in the combustion chamber is reduced, and stable combustion improves fuel efficiency. Further, the intake valve charging efficiency is improved by the early valve closing timing control, and the low speed torque can be increased.

[0010]

However, in the device according to the prior application, the operating angle of the intake valve 4 is controlled to be small by the eccentric control of the annular disc 16 in the low engine speed region as described above. Although the valve opening timings are substantially the same and the valve closing timings are set sufficiently early to improve the fuel consumption, the engagement grooves 11 and 18 are formed as shown in FIGS. 14 and 15, respectively. Since the flanges 10 and 13 are formed along the radial lines F1 and F2 passing through the centers X of the flanges 10 and 13, the eccentric amount of the annular disk 16 with respect to the drive shaft 1 is naturally restricted by the length of the engaging grooves 11 and 18. It is difficult to obtain a larger amount of eccentricity. As a result,
The rotational phase difference between the drive shaft 1 and the camshaft 2 is also limited to the predetermined range as described above, and therefore the angular velocity of the camshaft 2 and its change amount are also limited. Therefore, it becomes difficult to sufficiently improve the valve timing control accuracy according to the engine operating state.

[0011]

The present invention has been devised in view of the actual situation of the device according to the above-mentioned prior application, and the invention of claim 1 is a drive shaft which is rotationally driven by an engine, and the drive shaft. A camshaft which is provided on the outer periphery of the cam so as to be rotatable relative to the outer periphery of the camshaft and integrally has a cam for opening and closing the intake and exhaust valves; a first flange portion fixed to one end of the camshaft; and a predetermined portion of the drive shaft. A second flange portion that is fixed to the first flange portion and that faces the first flange portion; an annular disc that is interposed between the flange portions and is eccentrically movable with respect to the axis of the drive shaft; and both sides of the annular disc. Of the annular disc and the pin that are slidably engaged in the respective elongated engaging grooves formed on the outer peripheral sides of the flange portions, respectively. Intake and exhaust valve drive control with a drive mechanism for moving the heart In location, each of said engaging groove, and characterized in that it is formed in an inclined shape to the forward position in the rotational direction from the center side of the flange portions.

According to the invention of claim 2, each of the engaging grooves is formed in an arc shape.

[0013]

According to the first aspect of the present invention, for example, in the low engine speed range, each pin of the disk reciprocally slides in each engagement groove of each flange portion for each rotation of the drive shaft, and the disk is reciprocated. Is eccentrically moved with respect to the axis of the drive shaft. At this time, since each engagement groove is formed in an inclined shape to the front position in the rotational direction of each flange portion, each pin is The moving speed in the eccentric direction increases, and the position of each pin reaches the maximum advanced angle near the valve opening position of the intake / exhaust valve by the cam. Therefore, the time when the rotational phase difference between the drive shaft and the camshaft becomes zero becomes earlier, that is, the time when the rotational phase difference occurs becomes earlier, and the angular velocity of the camshaft with respect to the drive shaft rises compared to the previous application. As it does, the amount of change also increases. This makes it possible to increase the conversion rate of the valve operating angle without increasing the amount of eccentricity of the annular disk with respect to the drive shaft when the valve operating angle is controlled to be small.

Further, according to the second aspect of the invention, since the engagement groove is formed in an arc shape, it is possible to make the rotational phase difference characteristic of the camshaft relative to the drive shaft linear, and thereby, the eccentricity. When the lift waveform characteristic of the cam at the time is prevented from abruptly rising on the lift side, the lift side and the down side can be made bilaterally symmetrical, and the occurrence of irregular movement of the intake valve or the like can be sufficiently suppressed.

[0015]

1 to 6 show an embodiment in which the intake / exhaust valve drive control device according to the invention of claim 1 is applied to the intake side of a four-cylinder internal combustion engine. In FIG. A drive shaft 22 to which a rotational force is transmitted via a sprocket is a plurality of cam shafts which are arranged on the outer periphery of the drive shaft 21 so as to be rotatable relative to each other and coaxial with the center X of the drive shaft 21. The drive shaft 21 extends in the front-rear direction of the engine and is formed in an inner hollow shape in order to reduce the weight.

The camshaft 22 is divided into four parts in the longitudinal direction at a predetermined position in each cylinder from the direction perpendicular to the axis, and the drive shaft 21 is inserted into an insertion hole 22a formed in the internal axial direction. It is rotatably supported by cam bearings 52, 53 provided at the upper end of the cylinder head (not shown). In addition, as shown in FIG.
A plurality of cams 26 that open the intake valves 23 against the spring force of the valve springs 24 via the valve lifters 25 are integrally provided.

Further, a first flange portion 27 is integrally fixed to one divided end portion of each cam shaft 22, and the first flange portion 27 is part of the outer peripheral surface as shown in FIG. Has a substantially trapezoidal bulge 27b with a slanted tip edge, and slender linear first engagement that is slanted from the center side to the outside in the forward position direction of the rotation direction (arrow direction) The groove 30 is formed. That is, the first engaging groove 30
The bulging portion 2 is located not in the radial direction from the center of the first flange portion 27 but in the rotational direction forward from a predetermined portion of the inner peripheral surface deviated from the center to the rearward position in the rotational direction.
A notch is formed up to the tip edge of 7b, and the whole is formed in an inclined shape in the rotation direction. That is, the cam 26 is formed in an inclined shape in a direction that advances the drive shaft 21 at the initial lift position (when the intake valve 23 starts to open). In addition, in the circumferential direction of the outer surface of the first flange portion 27, an annular disc 2 described later is formed.
9. A projecting surface 27a that is in sliding contact with one side surface is integrally provided.

A sleeve 28 and an annular disc 29 are arranged between the first flange portion 27 of the camshaft 22 and the end portion of the other camshaft 22 facing the first flange portion 27.

One end of the sleeve 28 having a small diameter is rotatably inserted into the other end of the camshaft 22 on the other side, and is driven through a connecting shaft 31 penetrating diametrically at a substantially central position. It is connected and fixed to the shaft 21. In addition, at the other end of the sleeve 28, the first flange portion 2
A second flange portion 32 that faces 7 is integrally provided. As shown in FIG. 5, the second flange portion 32 has a first
Similar to the flange portion 27, it has a substantially trapezoidal bulge 32b on a part of the outer peripheral surface, and has a slender linear second inclined from the outer peripheral side to the front position direction in the rotation direction (arrow direction).
An engagement groove 33 is formed. The second engagement groove 33 is
It is formed symmetrically at a position opposite to the first engagement groove 30. That is, the bulging portion 32b located at the rear position in the rotation direction.
Is formed in an inclined shape from the tip to the front position direction in the rotation direction on the center side of the second flange portion 32. A protrusion surface 32, which is in sliding contact with the other side surface of the annular disk 29, is integrally provided on the outer surface of the second flange portion 32.

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 camshaft 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 supported on the inner peripheral surface of the disk housing 35 via the annular bearing 34. In addition, a pair of pins 36 and 37 that engage with the engagement grooves 30 and 33 are provided in the holding holes 29b and 29c that are formed through the opposing positions on the diameter line. The pins 36 and 37 project in the opposite directions to each other in the axial direction of the camshaft, and the bases of the pins 36 and 37 have holding holes 29b and 29b.
29c is rotatably supported and the engaging grooves 30, 3 are formed on both side edges of the tip portion as shown in FIGS.
A flat surface portion 36a, 36b, 37a, 37b having a width across flats is formed so as to come into contact with the facing inner surfaces 30a, 30b, 33a, 33b of No. 3.

As shown in FIGS. 1 to 3, the disk housing 35 has a substantially annular shape, and has a boss portion 35a at one end of the outer periphery and a pivot pin 3 penetrating the boss portion 35a.
8 is provided so as to be vertically swingable in FIG. 2, and the lever portion 35 is provided on the outer peripheral surface opposite to the boss portion 35a.
b is projected along the radial direction. The disc housing 35 is swung by a drive mechanism 39 via a lever portion 35b.

As shown in FIGS. 2 and 6, the drive mechanism 39 includes first and second cylinders 40 and 41 formed facing a predetermined portion of the cylinder head, and the respective cylinders 40 and 41.
41, a hydraulic piston 42 and a plunger 43, which are provided so as to be retractable from within 41 and hold the arcuate tip end of the lever portion 35a from above and below at each tip edge, and the first cylinder 40.
And a hydraulic circuit 44 for moving the hydraulic piston 42 forward and backward by supplying and discharging hydraulic pressure to and from the pressure receiving chamber 40a.

The plunger 43 provided in the second cylinder 41 is formed in a substantially cylindrical shape having a bottom, and the spring force of the coil spring 45 elastically mounted in the second cylinder 41 causes the plunger 43 to advance (toward the lever portion). Is urged by.

The hydraulic circuit 44 has an oil passage 47 having one end communicating with the inside of the oil pan 46 and the other end communicating with the pressure receiving chamber 40a, and an oil pump 48 provided on the oil pan 46 side of the oil passage 47. And a 3-port 2-position electromagnetic switching valve 49 provided on the downstream side of the oil pump 48. The electromagnetic switching valve 49 switches the flow passage by an ON-OFF signal from the controller 50 that detects the current engine operating state based on signals such as the engine speed and the intake air amount, and the oil passage 47 is activated by the ON signal. While communicating with the whole, the oil passage 4 by the OFF signal
7 and the drain passage 51 are communicated with each other.

The operation of this embodiment will be described below.

At the time of high engine speed, when an ON signal is output from the controller 50 which has detected such an operating state to the electromagnetic switching valve 49, the hydraulic oil pumped from the oil pump 48 to the oil passage 47 is directly sent to the pressure receiving chamber 40a. Supplied. Therefore, as the internal pressure of the pressure receiving chamber 40a rises, the hydraulic piston 42 pushes up the lever portion 35b against the spring force of the coil spring 45 as shown by the solid line in FIGS. 29
The rotation center Y of the drive shaft 21 and the center X of the drive shaft 21 coincide with each other. In this case, no rotational phase is generated 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 are also aligned, so the rotational phase difference between the two 22 and 29 is the same. Does not occur. Therefore, as the drive shaft 21 rotates, the sleeve 28 rotates synchronously via the connecting shaft 31, and the engagement groove 33 and the pin 3 on the second flange portion 32 side.
7, annular disc 29, pin 36, first flange portion 27
The camshaft 22 also rotates synchronously via the side engagement groove 30. Therefore, the intake valve 23 has a large valve operating angle as shown by the alternate long and short dash line in FIG. 7B, and the valve closing timing is sufficiently delayed. As a result, intake charging efficiency is improved and high output torque is obtained.

On the other hand, when the engine speed is low, the controller 5
An OFF signal is output from 0 to the electromagnetic switching valve 49 to shut off the upstream side of the oil passage 47 and connect the downstream side of the oil passage 47 and the drain passage 51. Therefore, the pressure receiving chamber 40a
The hydraulic oil inside flows back through the oil passage 47 and is returned from the drain passage 51 into the oil pan 46.
The hydraulic piston 42 moves backward through the plunger 43 by the spring force of the valve spring 24 and the coil spring 45 as the internal pressure of a decreases. As a result, the disc housing 35 is pushed down by the plunger 43 as shown by the alternate long and short dash line in FIGS. 2 and 6, and swings downward with the pivot pin 38 as the fulcrum, and the center Y of the annular disc 29 is located on the drive shaft 21. Eccentric with center X. Therefore, the locking groove 33 of the second flange portion 32, the pin 37, and the first flange portion 27.
The sliding position between the locking groove 30 and the pin 36 of the drive shaft 21 is 1
It reciprocates with each rotation, and the angular velocity of the annular disk 29 changes, resulting in unequal angular velocity rotation.

That is, when one pin 37 slides in the engagement groove 33 and moves away from the center X of the drive shaft 21, and the other pin 36 slides in the engagement groove 30 and approaches the center X, The annular disc 29 has a large angular velocity with respect to the drive shaft 21, and the angular velocity of the camshaft 22 also increases. Therefore, the camshaft 22 is in a state in which the speed is doubled with respect to the drive shaft 21. As a result, the cam shaft 22 and the cam 2
The rotation phase difference between 6 and the drive shaft 21 changes as shown in FIG. 7A. Therefore, as shown by the solid line in FIG. 7B, the intake valve 23 has a small valve operating angle (valve timing) while the valve lift is constant, and the valve closing timing is sufficiently advanced. Therefore, the intake charging efficiency is improved and the low speed torque is improved.

During the eccentricity control of the annular disc 29, the engaging grooves 30, 33 are formed in a relatively inclined shape in the rotational direction of the flange portions 27, 32 as described above. As shown by N in FIG. 8, the moving speeds of the pins 36 and 37 in the eccentric direction in the engaging grooves 30 and 33 are sufficiently increased as compared with M in the case of the prior application, and the cams 26 and 26 are
The positions of the pins 36 and 37 near the valve opening positions (N) of the intake valves 23 and 23 due to are in the maximum advance (θ2) state. For this reason, the time when the rotational phase difference between the drive shaft 21 and the camshaft 22 becomes zero becomes earlier, in other words, the two 21, 21
When the rotational phase difference of 2 occurs earlier, the N
The rotational phase difference at the position also becomes sufficiently large (θ2). Therefore, the angular velocity of the camshaft 22 with respect to the drive shaft 21 increases more than that of the prior application, and the amount of change thereof also increases. As a result, as shown in FIG. 7B, it is not necessary to shift the cam lift central angle Q in the small control of the valve operating angle to the advance side (the direction of the arrow). Therefore, as shown in FIG. It is possible to increase the rate of change (α−β / α) of the operating angle of the intake valve 23 in comparison with the eccentricity amount of 29 as compared with the previous application (broken line).

In summary, both the effect of advancing the valve operating angle due to the eccentric movement of the annular disc 29 and the effect of advancing the movement of the pins 36 and 37 due to the inclined shapes of the angular engaging grooves 30 and 33 are provided. It is possible to increase the angular velocity and increase the amount of change without increasing the eccentricity of the valve 29. Therefore, the conversion rate of the valve operating angle can be made larger than that of the prior application.

As a result, the valve opening timing of the intake valve 23 is substantially the same as the concentric state, but the valve closing timing can be further advanced, and the valve timing control accuracy can be further improved.

On the other hand, conversely, when the valve operating angle conversion rate is set to be the same as in the prior application, the eccentric amount of the annular disk 26 can be reduced by that amount, so that the pin with respect to the engaging grooves 30 and 33 can be reduced. The sliding amount of 36 and 37 can be further reduced. Therefore, the friction is reduced and the mechanical load on the annular disk 26, the drive shaft 21 and the like can be reduced.

FIGS. 10 and 11 show an embodiment according to the invention of claim 2, in which the pins 36 and 37 are formed in a cylindrical shape and the flange-like engaging grooves 3 of the flange portions 27 and 32 are formed.
0 and 33 are formed in an arc shape along the rotation direction.

Therefore, it is of course possible to obtain the same effect as that of the above-mentioned embodiment, and the pins 36 and 37 are arcuate surfaces 36a and 36 of the engaging grooves 30 and 33 during the eccentricity control.
In order to make the annular disc 26 eccentric while rolling along b, 37a, 37b, as shown in FIG.
It is possible to make the rotational phase difference of the camshaft 22 with respect to the linear characteristic. As a result, the cam lift characteristic of the annular disc 26 when it is eccentric is prevented from abruptly rising on the lift side, and the lift side down side has a bilaterally symmetrical shape. Therefore, it is possible to sufficiently suppress the occurrence of irregular motion such as jumping or bouncing of the intake valve 23. Such action and effect are particularly effective in suppressing irregular movements that are likely to occur when the low-speed range is switched to the high-speed range.

[0035]

As is apparent from the above description, according to the present invention, since each engaging groove is formed in a slanted shape in the front position direction of the rotation direction, the angular velocity of the cam shaft with respect to the drive shaft is compared with that of the previous application. As it rises, the amount of change also increases. This makes it possible to increase the conversion rate of the valve operating angle without increasing the amount of eccentricity of the annular disk with respect to the drive shaft. As a result, the valve timing control accuracy is improved, and it is possible to further improve the combustion efficiency, for example, in the low rotation speed range.

According to the second aspect of the invention, it is possible to make the rotational phase difference between the drive shaft and the cam shaft a linear characteristic. Therefore, the cam lift waveform becomes bilaterally symmetrical, and irregular movement such as jumping of the valve can be suppressed.

[Brief description of drawings]

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

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 view showing a driving means of this embodiment.

7A is a characteristic diagram of a rotational phase difference between a drive shaft and a camshaft, and B is a valve lift characteristic diagram of a cam according to the present embodiment.

FIG. 8 is an explanatory view showing the positions of the engagement grooves at the time of concentricity and at the time of eccentricity in this embodiment.

FIG. 9 is a characteristic diagram showing the operation conversion rate of the present embodiment.

FIG. 10 is a BB of FIG. 3 showing an embodiment of the invention of claim 2;
FIG.

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

FIG. 12 is a characteristic diagram of the rotational phase difference between the drive shaft and the cam shaft of this embodiment.

FIG. 13 is a sectional view of the intake / exhaust valve drive control device of the prior application.

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

FIG. 15 is a sectional view taken along line EE of FIG.

16A is a characteristic diagram of a rotational phase difference between a drive shaft and a camshaft in the device of the prior application, and B is a valve lift characteristic diagram of the device.

[Explanation of symbols]

 21 ... Drive shaft 22 ... Cam shaft 27 ... 1st flange part 29 ... Annular disk 30, 33 ... Engagement groove 32 ... 2nd flange part 35 ... Disk housing 36, 37 ... Pin 39 ... Drive mechanism

Claims (2)

[Claims] 1. A drive shaft rotatably driven by an engine, and a cam shaft integrally provided on the outer periphery of the drive shaft so as to be rotatable relative to the drive shaft, the cam shaft integrally opening and closing an intake / exhaust valve.
A first flange portion fixed to one end portion of the camshaft, a second flange portion fixed to a predetermined portion of the drive shaft and facing the first flange portion, and interposed between the both flange portions, An annular disc that can be eccentrically moved with respect to the axis of the drive shaft, and elongated engagement grooves formed on the outer peripheral sides of the flange portions that project from opposite sides of the annular disc in opposite directions. In an intake / exhaust valve drive control device comprising a pin slidably engaged with the drive shaft and a drive mechanism for eccentrically moving the annular disc in accordance with an engine operating state, The intake / exhaust valve drive control device for an internal combustion engine, wherein the intake / exhaust valve drive control device is formed so as to be inclined from the front to the front in the rotational direction. 2. The intake / exhaust valve drive control device for an internal combustion engine according to claim 1, wherein each of the engagement grooves is formed in an arc shape.