JPH0742514A - Intake/exhaust valve driving control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption at the time of low rotation sharply, and improve output torque while suppressing irregular operation of a valve. CONSTITUTION:Rotational phase difference of a cam shaft 22 against a driving shaft 21 is generated by a control mechanism 23 interposed between the driving shaft 21 and the cam shaft 22 so as to change an angular speed. The opening/ closing timing of an intake valve is advance/delay-controlled by a variable valve timing mechanism 24 provided on the one end part of the driving shaft 21. The top point of the operating angle of the intake valve is set to the same phase point during change of rotational phase by the control mechanism 23, while the closing timing of the intake valve is controlled to an advance side by the variable valve timing mechanism 24.

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 FIG. 9. This intake / exhaust valve drive control device includes a hollow drive shaft 1 to which a rotational force is transmitted from a crankshaft of a multi-cylinder engine via a sprocket, and the drive shaft. A camshaft 2 is provided rotatably coaxially with the outer periphery of the shaft 1 and is divided into cylinders, and a control mechanism 3 is provided between the divided ends of the camshafts 2.

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 that are opened to resist the spring force of the valve springs 5 and 5 via a, and is rotatable by a pair of cam bearings 8 and 9 on the cylinder head 7. Supported by.

The control mechanism 3 has an annular first flange portion 10 integrally provided at one end portion of each camshaft 2.
Is fixed to a predetermined outer peripheral position of the drive shaft 1 by a connecting pin 11 via a sleeve 12, and the first flange portion 10
An annular second flange portion 13 facing each other, and a substantially annular disk housing interposed between the flange portions 10 and 13 so as to be swingable in a substantially radial direction from the axis X of the drive shaft 1. 14 and an annular disc 16 rotatably held in a large-diameter support hole 14a provided in the inner periphery of the disc housing 14 via a plain bearing 15. 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, elongated engaging grooves 17 and 18 are formed in the outer peripheral portions of the first and second flange portions 10 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 disc 16, the engaging grooves 17, 1 are projected in opposite directions.
Pins 19 and 20 engaging with 8 are projectingly provided.

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 center of 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 eccentric from the axis X of the drive shaft 1 via the disk housing 14 by the drive mechanism, so that the pins 19 and 20 of the engagement grooves 17 and 18 are formed. When the pin 20 on one side approaches the axis X of the drive shaft 1 by sliding in the radial direction along the inner peripheral surface, the pin 19 on the other side moves away from the axis X. Therefore, in this case, the disc 16 has a large angular velocity with respect to the drive shaft 1, and the camshaft 2 also has a large angular velocity with respect to the disc 16. 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. 10A, and when the angular velocity of the camshaft 2 is relatively large, the rotational phase with respect to the drive shaft 1 is both 1. 2 advances until the speed becomes constant, and then the angular velocity of the camshaft 2 becomes relatively small, the rotational phase delays until both 1 and 2 become uniform. And
The in-phase point P exists in the middle of the maximum and minimum points of the rotational phase difference, and when the rotational phase changes in FIG.
As shown by the one-dot chain line in B, the valve opening timing before the P point is delayed, and the valve closing timing after the P point is advanced, so that 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.

On the other hand, as a means for improving fuel efficiency in a low rotation speed range, a variable valve timing mechanism as disclosed in, for example, Japanese Patent Laid-Open No. 2-241914 is generally known. A cylindrical gear having helical teeth formed on its circumference converts the relative rotational phase of a rotary member such as a sprocket and a cam shaft to control the intake valve closing timing earlier.

[0012]

However, in the intake / exhaust valve drive control device according to the prior application, as described above, the large operating angle (solid line in FIG. 10B) and the small operating angle (see FIG. 10B) of the intake valve 4 are used. 1
The crossing point of the lift waveforms (the one-dot chain line of 0B), that is, the switching point Z between the large and small operating angles, is set to the drive shaft 1 and the camshaft 2.
The lift rising speed (acceleration) of the cams 6, 6 during the small operating angle control is likely to be large because the positions are set to correspond to the same phase point (point P). Therefore, the intake valve 4
However, during the opening operation, there is a possibility of causing irregular movement such as jumping or bouncing due to the spring force of the valve spring 5. Also, the maximum lift point of the large and small operating angles (vertices Q1, Q2
Is deviated from the point P to the retard side, the conversion ratio of the working angle to the eccentric amount of the annular disk 16 (α-β / α × 1
It is difficult to further increase 00). As a result, the control accuracy of the valve timing cannot be improved.

Therefore, as shown in FIG. 11, by setting the vertices Q1 and Q2 of the large and small operating angles above the point P, the lift rising speed of the cams 6 and 6 at the small operating angle as described above is reduced. Therefore, it is also considered that the irregular movement of the intake valve 4 is suppressed and the operating angle conversion rate is increased.

However, if such control is performed, not only can the valve closing timing of the intake valve 4 at a small operating angle be advanced earlier than the valve closing timing at a large operating angle. , The valve closing time is delayed. For this reason, pumping loss of the engine occurs, which adversely affects fuel efficiency.

On the other hand, when the conventional variable valve timing mechanism is used to simply advance the opening / closing timing of the intake valve as shown by the broken line in FIG. 12, the intake air is shown by the hatched line in the drawing. There is a possibility that the overlap between the valve and the exhaust valve becomes large and the back flow of the residual gas to the intake passage deteriorates the combustion, resulting in deterioration of engine performance (surge torque).

[0016]

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems of the device according to the above-mentioned prior application, and a drive shaft that is rotationally driven by an engine via a rotating member, and the drive shaft of the drive shaft. The camshaft is provided between the drive shaft and the camshaft, which is provided on the outer periphery so as to be relatively rotatable and integrally has a cam for opening and closing the intake and exhaust valves, and is interposed between the drive shaft and the camshaft. By changing the rotation phase of the camshaft,
A control mechanism that variably controls the magnitude of the operating angle of the intake and exhaust valves, and a variable valve timing mechanism that variably controls the opening and closing timing of the intake and exhaust valves by converting the relative rotational position of the rotating member and the drive shaft. In the intake / exhaust valve drive control device provided, while setting the apex of the operating angle of the intake / exhaust valve controlled by the control mechanism to substantially the same phase point during the rotation phase change of the drive shaft and the camshaft, At the time of controlling the small operating angle of the intake / exhaust valve, at least the closing timing of the intake / exhaust valve is controlled to the advanced side by the variable valve timing mechanism.

[0017]

According to the present invention having the above-described structure, since the apex of the operating angle of the intake valve controlled by the control mechanism is set to the substantially rotational in-phase point of the drive shaft and the cam shaft, the small operating angle control is performed. The lift speed of the cam is suppressed,
It is possible to prevent the occurrence of irregular movement during the opening operation of the intake valve,
Further, it becomes possible to further increase the operating angle conversion rate with respect to the eccentric amount of the annular disk.

Moreover, during such a small operating angle control, the variable valve timing mechanism controls the closing timing of the intake valve to the advanced side, so that the valve closing timing can be advanced while reducing the valve overlap. This prevents the reverse flow of the residual gas and improves the combustion efficiency.

[0019]

1 to 4 show an embodiment in which the intake / exhaust valve drive control device according to the present invention is applied to a four-cylinder engine having two intake valves per cylinder.

That is, reference numeral 21 in FIG. 1 denotes a drive shaft to which rotational force is transmitted from the crankshaft of the engine through a sprocket 56, which will be described later, and 22 denotes the drive shaft 21 fitted in an insertion hole 22a therein so as to be relatively rotatable. A camshaft inserted and arranged coaxially with the center X of the drive shaft 21, a control mechanism (VET) 23 for connecting the drive shaft 21 and the camshaft 22 to each other,
Is a variable valve timing mechanism (VTC) attached to one end of the drive shaft 21 and connected to the crankshaft via a timing chain.

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, and a large diameter first journal on the front end side is rotated on the cylinder head 7 by a bracket. It is supported freely.

The camshaft 22 is divided into four parts for each cylinder of the engine in the direction perpendicular to the axis, and each divided part is rotatably supported by a pair of cam bracket bearings 5, 5 on the cylinder head 7. ing. Further, at a predetermined position on the outer circumference of each cam shaft 22, as shown in FIG. 3, a pair of intake valves 4, 4 are opened against the spring force of the valve springs 5, 5 via the valve lifters 4a, 4a. Cams 25, 26 are integrally provided.

In each of the control mechanisms 23, the first control mechanism is disposed between the first journal and the first cylinder, and the second to fourth control mechanisms are the first and second, the second and third, and the third. The first flange portion 2 is disposed between the third and fourth cylinders, and is integrally provided at one end portion of each camshaft 22 on the engine front end side.
7, a second flange portion 32 provided on a predetermined outer periphery of the drive shaft 21 via a sleeve 28 and facing the first flange portion 27, and an annular disc interposed between the both flange portions 27, 32. 29 and a disk housing 35 that rotatably supports the outer circumference of the annular disk 29 on the inner peripheral surface of the support hole 35a via a bearing 34.

As shown in FIG. 4, the first flange portion 27 is provided with an elongated rectangular engaging groove 30 extending in the radial direction from the hollow portion, and the outer surface thereof is annular in the circumferential direction. A protruding surface 27a that is in sliding contact with one side surface of the disk 29 is integrally provided. On the other hand, the second flange portion 32 is
The sleeve 28 is integrally provided on the rear end side of the engine, and an elongated rectangular engaging groove 33 extending in the radial direction is formed at a position opposite to the engaging groove 30 by 180 °. A projecting surface 32a that is in sliding contact with the other side surface of the disk 29 is integrally provided.

Each of the sleeves 28 has one end portion 28a having a small step diameter rotatably inserted into the other end portion of each cam shaft 22, and is formed so as to penetrate substantially in the center position and in the diameter direction of the drive shaft 1. It is connected and fixed to the drive shaft 21 by a connecting pin 31 inserted through the through hole.

The annular disc 29 has a substantially toroidal plate shape, an inner diameter thereof is substantially equal to 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, 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 at the opposite positions on the diametrical line in the axial direction so as to penetrate therethrough. The pins 36 and 37 project in opposite directions in the axial direction of the camshaft 22, and the bases of the pins 36 and 37 have holding holes 29.
b and 29c are rotatably supported and the engaging groove 3 is formed on both side edges of the tip portion as shown in FIGS.
No. 0, 33 facing inner surfaces 30a, 30b, 33a, 33b, and flat surface portions 36a, 36b, 37a, 3 having a width across flats.
7b is formed.

As shown in FIGS. 1 to 3, the disk housing 35 has a substantially annular shape, and a pivot pin 38 inserted into an insertion hole of a boss portion 35a provided at one end of the outer circumference serves as a fulcrum to move the disk housing 35 up and down in FIG. On the other hand, a lever portion 35b is provided on the outer peripheral surface on the side opposite to the boss portion 35a so as to project in the radial direction. The disc housing 35 is swung by a drive mechanism 39 via a lever portion 35b. Incidentally, the pivot pin 38
Is fixed to the upper end of the cylinder head 7 via a bracket.

As shown in FIGS. 3 and 6, the drive mechanism 39 includes first and second cylinders 40 and 41 formed to face predetermined portions of the cylinder head 7, and the cylinders 40 and 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 35b 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 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 control mechanism 23 is shown in FIGS.
As shown in, the peak of the operating angle of the intake valve 4 by the cams 25 and 26 of the camshaft 22 (the peak of the cam lift waveform) Q
1 and Q2 are set to a rotational phase difference of zero between the drive shaft 21 and the camshaft 22, that is, the same phase point P.
That is, in the control mechanism 23, the center Y of the annular disk 29 and the axis X of the drive shaft 21 are aligned with each other at the time of high engine rotation, as in the device of the prior application, so that the drive shaft 21 and the cam shaft 22 are
Therefore, the rotation angle difference between the intake valve 4 and the intake valve 4 is not controlled so that the operating angle of the intake valve 4 is largely controlled as shown by the solid line in FIG. On the other hand, in the low rotation range, the drive mechanism 39 causes the disc housing 35 to oscillate and the center Y of the annular disc 29 is also controlled so as to be eccentric from the axis X of the drive shaft 21 for each rotation of the drive shaft 21. As a result, the operating angle is controlled to be small as shown by the alternate long and short dash line in FIG. 7B. Here, in the present embodiment, as described above, the vertices Q1 and Q2 of the cam lift waveforms of the large operating angle and the small operating angle are located at the positions that coincide with the in-phase point P of the relative rotation between the drive shaft 21 and the cam shaft 22. It is set.

On the other hand, the variable valve timing mechanism 24
As shown in FIG. 1, a sleeve 55 fixed to a collar portion 21a at one end of the drive shaft 21 by a fixing bolt 54, and a rotational force from a crankshaft arranged on the outer periphery of the sleeve 55 via a timing chain. And a cylindrical gear 57 interposed between the sleeve 55 and the cylindrical main body 56a of the sprocket 56.

The sleeve 55 has the flange portion 2 on the rear end side.
It has a large diameter portion 55a integrally fitted and fixed to 1a, and outer teeth are formed on the outer periphery.

The sprocket 56 is a cylindrical body 56a.
Is rotatably supported on the outer circumference of the large-diameter portion 55a, and inner teeth are formed on the inner circumference of the front end of the cylindrical main body 56a, and the front end opening is liquid-tightly sealed by the front cover 58. There is.

The cylindrical gear 57 is formed by dividing a long gear into two pieces in a direction perpendicular to the axis, and on the inner and outer circumferences thereof, a helical tooth-shaped inner and outer tooth 57 which spirally meshes with the inner and outer teeth.
a and 57b are formed. In addition, this cylindrical gear 57
Is moved in the front-rear axis direction by a different drive mechanism.

This drive mechanism is formed between the front cover 58 and the cylindrical gear 57, and has a pressure chamber 59 for moving the cylindrical gear 57 backward by the internal hydraulic pressure, and a hydraulic chamber for the pressure chamber 59. Is installed between the hydraulic circuit (not shown), the cylindrical gear 57 and the large diameter portion 55a, and the cylindrical gear 5
7 and a compression spring 60 that biases 7 in the forward direction.

When the engine is running at low and medium speeds, an ON signal is output from the controller for detecting the engine operating state to the electromagnetic switching valve of the hydraulic circuit, the hydraulic pressure is supplied into the pressure chamber 59, and the cylindrical gear 57 moves backward. When the intake valve 4 is moved, the sprocket 56 and the drive shaft 21 are relatively rotated in one direction at the same time.
Controls to advance the opening / closing timing of. On the other hand, when the engine is idling and at high speed, the solenoid switching valve is turned off.
When a signal is output and the tubular gear 57 moves forward by the spring force of the compression spring 60 as the hydraulic pressure in the pressure chamber 59 decreases, at the same time, both 21, 56 relatively rotate in the other direction and the intake valve 57 moves. Control for retarding the opening / closing timing of No. 4 is performed.

Therefore, according to this embodiment, the control mechanism 23 controls the valve operating angle to a small value as shown by the one-dot chain line in FIG. The control is performed so as to match the rotational in-phase point P of the drive shaft 21 and the cam shaft 22.

At the same time, the variable valve timing mechanism 24
However, as the cylindrical gear 57 moves backward, the sprocket 56 and the drive shaft 21 are relatively rotated to one side to convert the phase, and the small operating angle is controlled to the advance side as shown by the broken line in FIG. 7B.

Therefore, the above-mentioned control action of the control mechanism 23 suppresses the lift rising speed of the cams 25, 26, and prevents the occurrence of irregular motion such as jumping or bounce during the opening operation of the intake valve 4, and at the same time, the annular shape. Even if the eccentricity of the disk 29 is small, a sufficiently large operating angle conversion rate (α-β / α
X100) is obtained.

In addition, the control operation of the variable valve timing mechanism 24 makes it possible to particularly accelerate the valve closing timing while maintaining the valve opening timing of the intake valve 4 substantially the same as the large operating angle. Therefore, the reverse flow of the residual gas to the intake passage is sufficiently prevented, and the combustion efficiency can be improved.

As a result, the fuel consumption can be greatly improved when the engine speed is low, and the output torque is increased as shown by the hatched line in FIG. Further, even when the control mechanism 23 gradually increases the valve operating angle to the medium operating angle when the engine is shifted to the middle rotational speed range, the variable valve timing mechanism 24 still causes the variable valve timing mechanism 24 to advance the intake valve 4 (ON state). (State) is maintained, sufficient medium speed torque can be secured.

In the high engine speed range (for example, 5,000 rpm)
In the above case, the control mechanism 23 largely controls the valve operating angle as described above, and the variable valve timing mechanism 24 is turned off to retard the intake valve 4, so that the valve opening timing is early. At the same time, the valve closing timing is further delayed, the valve overlap is increased, and the intake charging efficiency is greatly improved. As a result, a sufficiently high output torque is obtained as shown in FIG.

During the idling operation, the control mechanism 23
The valve operating angle is controlled to a small angle by the variable valve timing mechanism 24 in the same manner as during high rotation. As a result, the valve overlap is reduced, a good combustion state is obtained, and the fuel consumption is improved and the rotation speed is stabilized.

[0045]

As is apparent from the above description, according to the present invention, the apex of the valve operating angle is set to the rotational in-phase point of the drive shaft and the cam shaft by combining the control mechanism and the variable valve timing mechanism. In addition, since the valve operating angle is controlled to the advanced side when the operating angle is small, it is possible to suppress irregular movement of the valve, especially in the low engine speed region, and to greatly improve the fuel consumption and obtain a large low speed torque. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a plan view of a main part of this embodiment.

FIG. 3 is a view on arrow A in FIG.

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 of a drive mechanism used in this embodiment.

7A is a rotational phase difference characteristic diagram of a drive shaft and a camshaft, and B is a valve lift characteristic diagram.

FIG. 8 is a characteristic diagram of engine speed and output torque according to the present embodiment.

FIG. 9 is a cross-sectional view of the main part of the device according to the prior application.

FIG. 10 is a diagram showing a rotational phase difference characteristic and a valve lift characteristic of a drive shaft and a cam shaft according to the device of the prior application.

FIG. 11 is a valve lift characteristic diagram of the device of the prior application.

FIG. 12 is a characteristic diagram of valve opening / closing timing by a variable valve timing mechanism.

[Explanation of symbols]

 4 ... Intake valve 21 ... Drive shaft 22 ... Cam shaft 23 ... Control mechanism 24 ... Variable valve timing mechanism 25, 26 ... Cam 56 ... Sprocket (rotating member).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seinosuke Hara Unisia Jecs Co., Ltd. 1370 Onna, Atsugi, Kanagawa

Claims (1)

[Claims] 1. A drive shaft which is rotationally driven by an engine via a rotating member, and a cam shaft which is provided on the outer periphery of the drive shaft so as to be rotatable relative to the drive shaft and integrally has a cam for opening and closing an intake / exhaust valve. A control mechanism that is interposed between the drive shaft and the cam shaft, and that changes the rotational phase of the cam shaft with respect to the drive shaft in accordance with the engine operating state to variably control the magnitude of the operating angle of the intake and exhaust valves; An intake / exhaust valve drive control device that includes a variable valve timing mechanism that variably controls the opening / closing timing of the intake / exhaust valve by converting the relative rotational position of the rotating member and the drive shaft, and is controlled by the control mechanism. The apex of the operating angle of the intake / exhaust valve is set to substantially the same phase point during the rotation phase change of the drive shaft and the camshaft, while the variable valve timing mechanism is used during the small operating angle control of the intake / exhaust valve. Intake and exhaust valve drive control device for an internal combustion engine, characterized in that control at least the closing timing to the advance side of the exhaust valve.