JPH10280927A - Drive controlling device of suction and exhaust valve for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the variable control of valve lifting characteristics easy by preventing phase deviation of the valve lift characteristics caused by the variation of eccentricity. SOLUTION: A cylindrical camshaft divided for each cylinder is fit rotatably on the circumference of a driving shaft 2 rotating synchronously with an engine. The camshaft rotates non-uniformly in accordance with the eccentric position of a circular disc 3 which interlocks both the shafts. The circular disc 3 is fitted into a control housing 6 and is held freely rotatable. The control housing 6 is guided with a guide rail 11 to to move in parallel, but takes an eccentric motion by an eccentric cam 13a of the control shaft 13. Thus, the moving locus of the center of the disc 3 becomes linear and no phase deviation occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the opening and closing of an intake valve and an exhaust valve according to the operating state of an internal combustion engine by rotating a cylindrical camshaft arranged on the outer periphery of a drive shaft at an unequal speed relative to the drive shaft. The present invention relates to an intake and exhaust valve drive control device that variably controls a timing and an operation angle.

[0002]

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

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

[0004]

However, in the above-described conventional intake / exhaust valve drive control device, the control housing is swingably supported and is eccentric from the center of the drive shaft by being swung by an eccentric cam or the like. Therefore, the movement trajectory of the center of rotation of the annular disk has a substantially arc shape. Therefore, the change in the valve lift characteristic with respect to the change in the amount of eccentricity becomes complicated, and it is difficult to obtain desired characteristics. FIG. 10 shows a change in the phase difference between the drive shaft and the camshaft. The valve lift characteristic changes as compared with the cam profile due to the phase difference. If it changes along a substantially arc-shaped trajectory, as shown in the figure, the point where the phase difference is 0 (the same phase point) also moves as indicated by Δθ, and the change in the valve lift characteristic becomes non-linear. is there.

In the V-type internal combustion engine, the layout of the intake and exhaust systems is symmetrical between the left and right banks, but the respective drive shafts rotate in the same rotational direction. According to the change in the eccentricity, the valve lift characteristic in one bank changes to the leading side and the other bank changes to the lagging side in the other bank, and the valve lift characteristics do not become completely the same. Problems also occur.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a drive shaft that rotates in synchronization with the rotation of an engine, an inner peripheral surface of which is rotatably fitted to an outer peripheral surface of the drive shaft, and an intake / exhaust valve. A cylindrical camshaft having a cam for driving the camshaft, a first flange portion provided at one end of the camshaft and having an engagement groove formed in a radial direction, and a first flange portion. A second flange portion provided on the drive shaft side so as to face and having an engagement groove formed in a radial direction; an annular disk disposed between the two flange portions; A pair of pins projecting in opposite directions and respectively engaging with the engagement grooves of both flange portions, and rotatably holding the annular disk,
A control housing movable along a direction perpendicular to an axis, wherein the valve lift characteristic is changed by eccentrically rotating the center of rotation of the annular disk via the control housing. The apparatus is characterized in that the control housing is guided by a guide rail so that the movement trajectory of the control housing is linear, and the rotation of the control shaft is transmitted to the control housing as linear motion.

In this configuration, as in the conventional case, when the center of rotation of the annular disk is concentric with the center of the drive shaft and the cam shaft, the drive shaft and the cam shaft rotate at a constant speed. When the annular disk is in the eccentric position, both rotate at an irregular speed. Therefore, the valve lift characteristic of the intake / exhaust valve changes continuously according to the position of the annular disk.

Here, in the present invention, the control housing is guided by the guide rail and always moves in parallel. That is, the movement locus of the center of rotation of the annular disk becomes a perfect straight line. Therefore, the change in the valve lift characteristics is simplified.

[0009] More specifically, in the invention of claim 2,
The control shaft has an eccentric cam, by which the rotation of the control shaft is transmitted to the control housing as a linear motion. In other words, the control housing, which is guided by the guide rail so as to be translated, is moved by the cam action of the control shaft, and the center of rotation of the annular disk is eccentric.

According to the third aspect of the invention, the rotation of the control shaft is transmitted to the control housing as a linear motion via the pinion rack mechanism. That is, the pinion is provided on the control shaft side, and the rotation causes the control housing including the rack to linearly move.

According to the fourth aspect of the present invention, the guide rails are engaged with both end surfaces of the control housing to restrict the movement of the control housing in the axial direction of the drive shaft.

In the invention according to claim 5, the guide rail is disposed between the valve lifter bores of the cylinder head. The annular disk and the control housing are provided between two adjacent cylinders, and a guide rail is disposed at a position sandwiched between valve lifter bores of both cylinders.

In the invention according to claim 6, the guide rail is provided on a straight line passing through the center of the control shaft having the eccentric cam and the center of the annular disk.
Therefore, the line of action of the force by the cam action substantially coincides with the direction of the guide rail, and no force is applied laterally at the sliding portion with the guide rail. Therefore, the control housing moves smoothly with the rotation of the control shaft.

Further, in the invention according to claim 7, the guide rail is located immediately below the drive shaft. The drive shaft and the camshaft on its outer periphery are forcibly lubricated by lubricating oil supplied from the cylinder head side. The guide rail is simultaneously lubricated by the lubricant oil flowing down.

[0015]

According to the intake / exhaust valve drive control apparatus for an internal combustion engine according to the present invention, the change in the valve lift characteristic is simple determined by the amount of eccentricity, and the control of the valve operating angle and the valve lift characteristic is facilitated. . Even when applied to a V-type internal combustion engine, the valve lift characteristics do not advance or delay due to the eccentricity, so that the characteristics of each cylinder can always be kept the same.

According to the fourth aspect of the present invention, it is possible to prevent the control housing from falling down and to prevent an increase in friction and uneven wear of the annular disk due to the control housing falling down.

According to the fifth aspect of the present invention, the guide rail can be arranged by utilizing the space between the valve lifter bores, and the size of the entire cylinder head can be reduced.

According to the structure of claim 6, the movement of the control housing accompanying the rotation of the control shaft becomes very smooth, so that the required driving force can be reduced and the friction loss can be suppressed.

Further, according to the configuration of the seventh aspect, the guide rail can be simultaneously lubricated with the lubricating oil that has lubricated the drive shaft, the camshaft, and the like, and a special lubrication mechanism can be eliminated.

[0020]

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

FIG. 1 is a sectional view of a cylinder head 1 showing a main part of an intake / exhaust valve drive control device according to the present invention.

In this embodiment, a variable valve mechanism is provided on one of the intake and exhaust valves, for example, on the intake valve side, and is provided above the cylinder head 1 in parallel with an exhaust camshaft (not shown). A single drive shaft 2 is provided over all the cylinders. The drive shaft 2 has a sprocket (not shown) attached to one end thereof, and is linked with a crankshaft (not shown) together with an exhaust-side camshaft via a timing chain. A cylindrical camshaft (not shown) divided for each cylinder is fitted around the outer periphery of the drive shaft 2 so as to be relatively rotatable, and is provided at an end of each camshaft. An annular disk 3 having an annular shape is sandwiched between one flange portion (not shown) and a second flange portion (not shown) fixed to the drive shaft 2 side. A pair of pins 4 and 5 are provided on the annular disk 3 so as to protrude in opposite directions, respectively, and slidably engage with engagement grooves formed in the respective flange portions along the radial direction. I have.
The annular disk 3 is provided with a predetermined gap between its inner peripheral edge and the outer periphery of the drive shaft 2 so as to be eccentric with respect to the drive shaft 2. The annular disk 3 is rotatably fitted and held in a circular opening 7 of the control housing 6.

The eccentric type variable valve mechanism as described above has a known configuration in, for example, the above-mentioned Japanese Patent Application Laid-Open No. 6-185321, so that detailed description thereof will be omitted, but the state shown in FIG. If the annular disk 3 is located concentrically with respect to the center of the drive shaft 2, the camshafts rotate at a constant speed with respect to the drive shaft 2, and the valve lift characteristics along the profile of the cam can be obtained. Also annular disk 3
Is eccentric with respect to the center of the drive shaft 2, it becomes a kind of non-uniform speed joint, and each cam shaft rotates at non-uniform speed with respect to the drive shaft 2. As a result, the valve lift characteristics and the valve operating angle change.

The control housing 6 for holding the annular disk 3 has a plate shape along a plane orthogonal to the drive shaft 2, and a ring 6a surrounding the opening 7 is located at a central portion. A guide portion 6 is provided diagonally below the ring portion 6a.
b is formed as a rectangular extension, and diagonally upward,
A substantially square ear 6c is formed to extend. And
The distal end surface of the guide portion 6b is formed smoothly as the guide surface 8, and an elongated guide slit 9 is formed in parallel with the guide surface 8. Note that the guide slit 9 and the guide surface 8 are substantially along the tangential direction of the opening 7. A substantially rectangular cam fitting portion 10 having a pair of parallel cam contact surfaces 10a and 10b is formed in the ear 6c. The cam contact surface 10
Also, a and 10b are formed substantially along the tangential direction of the opening 7 and substantially perpendicular to the guide slit 9 and the guide surface 8.

The above guide surface 8 and guide slit 9
Corresponding to the guide rail 11 on the cylinder head 1 side.
Is provided. As shown in FIG. 2, the guide rail 11 has a base portion 11a extending in a rod shape having a rectangular cross section.
And a rail portion 11b projecting from the base portion 11a in an L-shaped cross section. The guide surface 8 slides on the upper surface of the base portion 11a, and the rail portion 11b slides on the guide slit 9. It is movably engaged. That is, the control housing 6 is guided by the guide rail 11 so as to move linearly.

The guide rail 11 has a base portion 11a.
Is fixed to the cylinder head 1 by bolts 12. In particular, the guide rail 11 is disposed in a recess formed between a pair of adjacent cylinders, more specifically, between the respective valve lifter bores, and the control housing 6 is mounted thereon. ing.

A control shaft 13 is arranged through the cam fitting portion 10 of the control housing 6 supported as described above. The control shaft 13 is arranged in parallel with the drive shaft 1 and is continuous to one over all cylinders. For example, the control shaft 13 is rotatably held on an upper portion of a cam bracket holding a cam shaft. At the same time, one end thereof is connected to a hydraulic actuator (not shown). A circular eccentric cam 13a is formed on the control shaft 13 at a position corresponding to the control housing 6 of each cylinder, and the eccentric cam 13a is connected to a pair of cam contact surfaces 10a of the cam fitting portion 10. , 10b without any gap.

Therefore, in the configuration of the above embodiment, when the control shaft 13 rotates, the control housing 6 reciprocates by the cam action of the eccentric cam 13a, and the eccentric amount of the annular disk 3 is variably controlled. In particular, the control housing 6 is linearly moved in the direction of arrow S in FIG. 1 under the control of the guide rail 11, so that the phase difference between the drive shaft 2 and the camshaft becomes zero. Is maintained at a constant cam angle regardless of the magnitude of the amount of eccentricity, and the change in the valve lift characteristic based on the phase difference becomes simple.

Further, in the above configuration, the guide rail 11 is arranged by utilizing the recess formed between the valve lifter bores, and the control housing 6 is mounted thereon. The dimensions in the width and height directions can be kept very small. The guide rail 1 is located below the drive shaft 2 and the annular disk 3.
Since 1 is located, the lubricating oil used for lubricating the drive shaft 2 and the annular disk 3 flows down, and the sliding portion between the guide rail 11 and the control housing 6 is simultaneously lubricated. Thereby, an increase in friction loss can be avoided.

Next, FIGS. 3 and 4 show a second embodiment of the present invention.
An example is shown. In this embodiment, the control housing 6
Guide portion 6b and corresponding guide rail 11
The guide groove 21 is recessed on both sides of the guide portion 6b having the guide surface 8 at the end, and the guide groove 11 is provided on both sides of the base portion 11a on the guide rail 11 side. Rail portion 11b engaging with guide groove 21
Is provided. In other words, the guide rail 11
A concave groove is formed in a substantially T-shaped cross section, and the distal end of the guide portion 6b is slidably fitted therein.

In the second embodiment, the control housing 6 is guided linearly by the guide rails 11 and is supported in both the axial direction of the drive shaft 2.
That is, the movement in the axial direction is reliably restricted by the fitting between the guide rail 11 and the guide portion 6b. Therefore, the control housing 6 does not tilt or fall down in the axial direction during operation, and it is possible to prevent an increase in friction loss and uneven wear of the fitting portion of the annular disk 3 due to the fall.

Next, FIGS. 5 and 6 show a third embodiment of the present invention.
An example is shown. In this embodiment, in the control housing 6, the ears 6c provided with the cam fitting portions 10 and 180
° A guide portion 6b is formed in a substantially triangular shape on the opposite side,
Here, a guide slit 22 is formed along the radial direction of the circular opening 7. This guide slit 22
The center O1 of the control shaft 13 and the center O of the annular disc 3
2 and is formed along a straight line L passing through, and the tip is open.

A guide rail 23 provided on the cylinder head 1 side with respect to the guide slit 22 protrudes from the mounting portion 23a in an L-shaped cross section as shown in the figure.
The guide slit 22 is slidably fitted so as to sandwich the rail 23b at the tip.

In this embodiment, the control shaft 13
The force by the eccentric cam 13a acts on the guide rail 23 and does not generate a rotational moment about the guide rail 23. Therefore, the control housing 6 moves very smoothly, the driving force required for controlling the rotation of the control shaft 13 is reduced, and the friction loss can be suppressed.

Next, FIGS. 7 and 8 show a fourth embodiment of the present invention.
An example is shown. In this embodiment, in the control housing 6, a guide portion 6b is formed near a lower portion opposite to the ear portion 6c having the cam fitting portion 10, and a guide portion 6b is formed here.
A guide surface 24 and a guide slit 25 are formed. The guide slit 25 is formed in parallel with a straight line L passing through the center O1 of the control shaft 13 and the center O2 of the annular disk 3. And this guide slit 25
On the other hand, a guide rail 26 having a base portion 26a and a rail portion 26b is provided on the cylinder head 1 side. The rail portion 26b is fitted in the guide slit 25 and The guide surface 24 is in sliding contact with the upper surface. Particularly, in this embodiment, the guide portion 6b including the guide rail 26 is set so as not to protrude below a height range H determined by the diameter of the ring portion 6a.

Therefore, in this embodiment, the total height of the internal combustion engine can be reduced as compared with the embodiment of FIG.

FIG. 9 shows a fifth embodiment of the present invention. In this embodiment, a pinion rack mechanism is used to move the control housing 6 instead of the cam mechanism described above. That is, the control shaft 13 is provided with the pinion portion 27 and the control housing 6
The rack part 28 is formed, and both are engaged with each other. Thus, when the control shaft 13 rotates, the control housing 6 moves linearly along the guide rail 11.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a cylinder head showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view along the line AA.

FIG. 3 is a sectional view of only a main part showing a second embodiment of the present invention.

FIG. 4 is a side view of the main part.

FIG. 5 is a sectional view of only a main part showing a third embodiment of the present invention.

FIG. 6 is a side view of the main part.

FIG. 7 is a sectional view of only a main part showing a fourth embodiment of the present invention.

FIG. 8 is a side view of the main part.

FIG. 9 is a sectional view of only a main part showing a fifth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a change in a phase difference between a drive shaft and a camshaft in a conventional example.

[Explanation of symbols]

 2 ... drive shaft 3 ... annular disk 6 ... control housing 9 ... guide slit 11 ... guide rail 13 ... control shaft

Claims (7)

[Claims] A drive shaft that rotates in synchronization with rotation of the engine; and an inner peripheral surface fitted to an outer peripheral surface of the drive shaft so as to be relatively rotatable;
A cylindrical camshaft having a cam on the outer periphery for driving the intake / exhaust valve; a first flange portion provided at one end of the camshaft and having an engagement groove formed in a radial direction; A second flange provided on the drive shaft side to face the first flange portion and having an engagement groove formed in a radial direction;
A flange portion, an annular disk disposed between the two flange portions, a pair of pins projecting from the annular disk in opposite directions, and respectively engaging with engagement grooves of the two flange portions; A control housing that rotatably holds the disk and is movable along a direction perpendicular to the axis, wherein a valve lift characteristic is changed by decentering the rotation center of the annular disk via the control housing. In the intake / exhaust valve drive control device for an internal combustion engine, the control housing is guided by a guide rail so that the movement trajectory of the control housing is straight,
An intake / exhaust valve drive control device for an internal combustion engine, wherein rotation of a control shaft is transmitted to the control housing as linear motion. 2. The intake / exhaust valve drive of an internal combustion engine according to claim 1, wherein the control shaft has an eccentric cam, and the rotation of the control shaft is transmitted to the control housing as a linear motion by the eccentric cam. Control device. 3. The intake and exhaust valve drive control device for an internal combustion engine according to claim 1, wherein the rotation of the control shaft is transmitted to the control housing as a linear motion via a pinion rack mechanism. 4. The control rail according to claim 1, wherein the guide rails engage with both end surfaces of the control housing to restrict movement of the control housing in the axial direction of the drive shaft. Intake and exhaust valve drive control device for an internal combustion engine. 5. The intake / exhaust valve drive control device for an internal combustion engine according to claim 1, wherein the guide rail is disposed between valve lifter bores of a cylinder head. 6. The drive device according to claim 2, wherein the guide rail is provided on a straight line passing through the center of the control shaft and the center of the annular disk. 7. The intake / exhaust valve drive control device for an internal combustion engine according to claim 1, wherein the guide rail is located immediately below the drive shaft.