JPH07233715A - Intake/exhaust valve driving controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent occurrence of irregular movement such as the jumping of an intake valve during the eccentric controlling time of an annular disc, etc. CONSTITUTION:An annular disc 29 is freely swingably provided between the second flange part 32 of a driving axis 21 and the first flange part 27 of a camshaft 22 through a disc housing 35 by a driving mechanism. The constitution of an intake/exhaust valve driving controller of an internal combustion engine is premised in such a way that the angular velocity of the camshaft 22 against the driving axis 21 is changed in an eccentric position against the axial center X of the driving axis 21 of the annular disc 29. When the operating angle of an intake valve is controlled o the minimum extent following to the eccentric movement of the annular disc 29, the profile of the cam 26 is set in such a manner that a load pattern against a cam surface during a valve lifting time a the spring set load pattern curve of a valve spring are arranged approximately in parallel to each other having an approximate constant difference.

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. 10 to 12. 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.

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 disk 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 supports the support shaft. It is designed to swing around a drive mechanism. Furthermore, the first and second flange portions 10,
Elongated engaging grooves 17 and 18 are formed in the outer peripheral portion of the member 13 at positions of 180 ° from each other along the radial direction. on the other hand,
Pins 19 and 20 projecting in opposite directions to engage with the engaging grooves 17 and 18 are formed on both side surfaces of the annular disc 16.
Is projected.

Then, for example, when the engine rotates at high speed, the disk housing 14 does not swing and the center of the annular 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 not shown in the drawing is performed. Disk housing 14 by mechanism
Oscillates to move the annular disk 16 eccentrically with respect to the axis X of the drive shaft 1.

That is, for example, when the engine is rotating at high speed, the center of the annular disk 16 coincides with the axis X of the drive shaft 1 and the rotational phase difference between the drive shaft 1 and the cam shaft 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 valve operating angle 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 annular 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, so that the pins 19 and 20 are engaged with each other. When the one side pin 20 approaches the axial center X of the drive shaft 1 by sliding in the radial direction along the inner peripheral surfaces of the grooves 17 and 18, the other side pin 19 is separated from the axial center X. Therefore, in this case, the annular disc 16
Increases the angular velocity with respect to the drive shaft 1 and also increases the angular velocity of the camshaft 2. Therefore, the camshaft 2
Is in a state in which the speed is doubled with respect to the drive shaft 1. Therefore, when the rotational phase difference between the drive shaft 1 and the cam shaft 2 changes as shown in FIG. 13B and the angular velocity of the cam shaft 2 is relatively large, the rotational phase with respect to the drive shaft 1 is constant at both 1 and 2. Until the camshaft 2
When the angular velocity of becomes relatively small, the rotational phase becomes
Delay until 2 becomes constant speed.

As shown in FIG. 13B, an 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. 13B, the valve operating angle is indicated by the broken line in FIG. 13A. As shown, the valve opening timing before point P is delayed, and the valve closing timing after point P 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.

[0012]

By the way, in such an intake / exhaust valve drive control device, the engine performance is improved by variably controlling the valve operating angle during the cam lift according to changes in the engine operating state. As shown in the drawing, when the valve operating angle is controlled to be small at low speed, that is, when the valve opening timing is controlled to be shortened, the load on the cam surface during the lift of the cam 6 increases and the intake valve 4 is driven by the cam 6. There is a risk that the given lift curve will deviate and irregular movements such as jumping will occur.

That is, the inertial force (acceleration) of the intake valve 4 during the opening / closing operation, especially the negative load on the cam surface 6a at the time of the cam lift (when the intake valve 4 is open) increases to increase the spring set load of the valve spring. If it is larger than this, jumping or the like is likely to occur. Therefore, it is desirable to set such negative loads sufficiently small and set the profiles of the cams 6 and 6 so that the inertial force is always reduced by the spring set load of the valve spring.

However, in the above-mentioned conventional device, as shown in FIG. 15, the annular disc 16 is concentrically controlled by the drive shaft 1 at the time of high rotation so that the intake valve 4 has a large valve operating angle and a negative cam. When the load pattern curve (FC) on the surface 6a is controlled to be small, the valve spring 5
The spring set load pattern curve FS is determined and the cam profile is set so that both pattern curves FC and FS are substantially parallel.

For this reason, as described above, when the valve operating angle is controlled to be small at low rotation speed, the negative load increases and the substantially central portion F of the load pattern curve FC as shown in FIG.
C1 is almost equal to the spring set load pattern curve FS,
It becomes larger and jumping etc. occurs. As a result, not only the engine performance is deteriorated, but also the valve train may malfunction.

Therefore, if the spring set load of the valve spring 5 is increased in order to prevent the jumping or the like, the driving torque increases, the fuel consumption deteriorates, or the load on the base side of the cam surface 6a increases to increase the intake valve. There is a fear that seizure of 4 etc. will occur.

[0017]

The present invention has been devised in view of the problems of the above-mentioned prior application. The invention of claim 1 is a drive shaft which is rotationally driven by an engine, and the outside of the drive shaft. A cam shaft coaxially rotatably disposed and having a cam for driving an intake / exhaust valve on the outer peripheral surface, and a shaft of the drive shaft disposed coaxially with the drive shaft on the end side of the cam shaft. Equipped with an annular disc that can be eccentrically oscillated with respect to the center, and a drive mechanism that concentrically or eccentrically moves the annular disc with respect to a drive shaft, and obtains a change in the angular velocity of the camshaft with eccentric oscillation of the annular disc. In the intake / exhaust valve drive control device for variably controlling the operating angle of the intake / exhaust valve, a load pattern curve and a valve spring for the cam surface at the time of valve lift of the intake / exhaust valve when the operating angle is controlled to the minimum. Spring set load It is characterized in that the pattern curve has set the profile of the cam so as to be substantially parallel with the difference between the substantially constant.

According to a second aspect of the present invention, when the operating angle is variably controlled to the maximum, the load pattern curve for the cam surface of the intake / exhaust valve at the time of valve lift is substantially concave near the center of the valve lift. It is characterized in that the profile of the cam is set so as to be substantially flat.

[0019]

According to the first and second aspects of the present invention, when the annular disc is eccentrically oscillated and the valve operating angle is controlled to be small at a low engine speed, the negative acceleration range of the load pattern curve with respect to the cam surface is obtained. Even if the (approximately central portion) becomes large, it becomes substantially parallel to the spring load pattern curve of the valve spring with a constant difference, and is always smaller than the spring set load pattern. Therefore, the occurrence of jumping of the intake / exhaust valve is reliably prevented.

[0020]

3 to 6 show an embodiment in which the intake / exhaust valve drive control device according to the present invention is applied to the intake side of a four-cylinder internal combustion engine. In FIG. 3, reference numeral 21 denotes a crankshaft of the engine through a sprocket. A drive shaft to which the rotational force is transmitted, 22 is a plurality of cam shafts that are arranged on the outer periphery of the drive shaft 21 so as to be relatively rotatable, and are provided coaxially 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 internal hollow shape in order to reduce the weight.

The camshaft 22 is divided into four parts from the direction perpendicular to the axis for each cylinder at a predetermined position in the longitudinal direction, 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). Further, as shown in FIG. 4, a plurality of cams 26 for opening two intake valves 23 per cylinder at predetermined positions on the outer periphery of the camshaft 22 through the valve lifter 25 against the spring force of the valve spring 24. Are provided integrally.

Further, a first flange portion 27 is integrally fixed to one split end portion of each cam shaft 22. The first flange portion 27 extends from the hollow portion in the radial direction as shown in FIG. An elongated rectangular first engaging groove 30 is formed along with, and a protruding surface 27a that slidably contacts one side surface of an annular disk 29 described later is provided integrally in the circumferential direction of the outer peripheral surface thereof.

A sleeve 28 and a second flange portion 32 integrally formed with the sleeve 28 are arranged on the end side of the camshaft 22 on the other side facing the first flange portion 27 with a constant gap. An annular disk 29 is arranged between the facing surfaces of the first flange portion 27 and the second flange 32.

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. As shown in FIG. 7, the second flange portion 32 has an elongated rectangular engagement groove 33 formed in the radial direction on the side opposite to the first engagement groove 30 of the first flange portion 27 in the radial direction. In addition, the outer peripheral surface is integrally provided with a protruding surface 32a that is in sliding contact with the other side surface of the annular disk 29.

The annular disc 29 has a substantially donut 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, 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. 6 and 7.
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.

The disk housing 35 has a substantially annular shape as shown in FIGS. 3 to 5, 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. 4, 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. 4 and 8, 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 with 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 profile of the cam 26 is such that the cam surface 26 when the intake valve 23 is lifted when the annular disc 29 swings eccentrically with respect to the axis of the drive shaft 21.
Load pattern curve FC and valve spring 2 for a
The spring set load pattern curve FS of No. 4 is set to be substantially parallel with a substantially constant difference.

More specifically, the cam profile is such that, when the annular disk 29 is controlled concentric with the axis of the drive shaft 21 (large operating angle control), the cam profile during valve lift as shown in FIG. The center portion FC1 of the load pattern curve FC with respect to the surface 26a is set to be concave. Therefore, the spring set load pattern curve FS is formed so as to be slightly close to both sides of the center portion FC1 but to be largely separated near the center portion FC1. ing.

As a result, during the eccentricity control (small operating angle control) of the annular disk 29 as described above, as shown in FIG. 1, the load pattern curve FC and the spring set load pattern curve FS during the valve lift have a constant difference ( FS-F
In C), they are separated from each other and become substantially parallel to each other so that the load pattern curve FC does not always exceed the spring set load pattern curve FS.

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 lines 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 solid line in FIG. 13A, 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. 4 and 8 and swings downward with the pivot pin 38 as a fulcrum, and the center Y of the annular disc 29 is set to 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 separates 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. 13B. Therefore, the intake valve 23 has a small valve operating angle (valve timing) with a constant valve lift, as shown by the broken line in FIG. 13A, and the valve closing timing is sufficiently advanced. Therefore, the intake charging efficiency is improved and the low speed torque is improved.

Further, in this embodiment, as described above, the negative load pattern curve FC during the valve lift of the intake valve 23 does not exceed the spring set load pattern curve FS during the valve lift of the intake valve 23 as shown in FIG. Since it is always in a substantially parallel state, it is possible to reliably prevent occurrence of irregular movement such as jumping of the intake valve 23.

Moreover, since the load on the cam surface 26a is reduced without increasing the spring set load of the valve spring 24 to prevent jumping or the like, an increase in drive torque can be suppressed, fuel consumption is deteriorated, and intake valve 23 burns. Occurrence of sticking can be prevented.

When the valve operating angle is controlled to a large value at high engine speed, the central portion FC1 of the load pattern curve FC becomes concave as shown in FIG. 2, but the jumping of the intake valve 23 does not occur. Needless to say, it does not significantly affect the high output of the engine.

As another example, the profile of the cam 6 is set so that the center portion FC1 of the load pattern curve FC during the large control of the valve operating angle becomes substantially flat as shown by the alternate long and short dash line in FIG. Is also possible. Also in this case, the load pattern curve FC and the spring load pattern curve FS can be made substantially parallel to each other with a certain difference when the valve operating angle is controlled to be small. If the period in which the curves FC and FS are substantially parallel to each other with a constant difference is set to half the opening period of the intake valve 23, the intake amount of the engine is not reduced.
Since the valve opening acceleration of the intake valve 23 also does not increase sharply, stable output of the engine can be increased.

Further, FIG. 9 shows a different cam surface 26a.
The other example of the load pattern with respect to is shown. That is, the rotational phase difference of the camshaft 22 with respect to the drive shaft 21 is shifted so that the valve lift Y during the large operating angle control of the intake valve 23, that is, the valve opening / closing timing, and the valve lift Z during the small operating angle control, that is, the valve opening / closing timing. In the case of asymmetry, the negative load pattern curve FC (solid line) and the spring set load pattern curve FS at the time of small operating angle control are made substantially parallel to each other so that the negative load pattern curve FC is at a large operating angle. The profile of the cam 26 is set such that the valve opening side from the center is concave as shown by the broken line FC. Therefore, also in this case, the same effect as that of the above-described embodiment can be obtained.

The present invention is not limited to the above embodiments, and the negative load pattern curve FC and the spring set load pattern curve FS at the time of small operating angle control are always substantially parallel with a certain difference. It suffices if the cam profile can be set to, and the change in the valve opening / closing timing does not matter. Further, it goes without saying that the invention can be applied to the exhaust valve side as well as the intake valve.

[0043]

As is apparent from the above description, according to the intake / exhaust valve drive control device of the present invention, when the operating angle of the intake / exhaust valve is controlled to the minimum, the cam surface for the valve lift is lifted. Since the cam profile is set so that the load pattern curve is smaller than the spring set load pattern curve of the valve spring, it is possible to reliably prevent the occurrence of irregular motion such as jumping during the opening / closing operation of the intake / exhaust valve.

[Brief description of drawings]

FIG. 1 is a diagram showing a load pattern curve and a spring set load pattern curve for a cam surface during eccentricity control of an annular disc according to an embodiment of the present invention.

FIG. 2 is a diagram showing a load pattern curve and a spring set load pattern curve for a cam surface during concentric control of the annular disc of the present embodiment.

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

FIG. 4 is a view on arrow A in FIG.

FIG. 5 is a plan view showing a part of the present embodiment.

6 is a cross-sectional view taken along the line BB of FIG.

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

FIG. 8 is a schematic diagram showing a driving means of the present embodiment.

FIG. 9 is a characteristic diagram showing another example of the present invention.

FIG. 10 is a partially cutaway view of the device of the prior application.

11 is a sectional view taken along line DD of FIG.

12 is a cross-sectional view taken along the line EE of FIG.

13A is a characteristic diagram of a rotational phase difference between a drive shaft and a camshaft, and B is a valve lift characteristic diagram.

FIG. 14 is a diagram showing a load pattern curve and a spring set load pattern curve for a cam surface during eccentricity control of an annular disc in a prior application device.

FIG. 15 is a view showing a load pattern curve and a spring set load pattern curve for a cam surface at the time of concentric control of an annular disk in the prior application device.

[Explanation of symbols]

 21 ... Drive shaft 22 ... Cam shaft 23 ... Intake valve 24 ... Valve spring 26 ... Cam 29 ... Annular disc 35 ... Disc housing 39 ... Drive mechanism FC ... Load pattern curve for cam surface FS ... Spring set load pattern curve

Claims (2)

[Claims] 1. A camshaft, which is rotatably driven by an engine, a camshaft, which is disposed coaxially with the outside of the drive shaft so as to be relatively rotatable, and which has an outer peripheral surface for driving an intake / exhaust valve, and a camshaft. An annular disc disposed coaxially with the drive shaft on the end side of the drive shaft and eccentrically swingable with respect to the axis of the drive shaft; and a drive mechanism for concentrically or eccentrically moving the annular disc with respect to the drive shaft. In the intake / exhaust valve drive control device for variably controlling the operating angle of the intake / exhaust valve by obtaining a change in the angular velocity of the camshaft with the eccentric swing of the annular disc, when the operating angle is controlled to a minimum. The profile of the cam is set so that the load pattern curve on the cam surface at the time of valve lift of the intake / exhaust valve and the spring set load pattern curve of the valve spring are substantially parallel with a substantially constant difference. Intake and exhaust valve drive control device for an internal combustion engine, characterized in that the. 2. When the operating angle is variably controlled to the maximum, the load pattern curve for the cam surface of the intake / exhaust valve when the valve is lifted is substantially concave or substantially flat near the center of the valve lift. An intake / exhaust valve drive control device for an internal combustion engine, wherein the cam profile is set as described above.