JP2002013404A - Cam drive control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of durability caused as rattling and hammering is generated between both supporting surfaces of a movable cam against a camshaft in a state where a cam nose part advances in the maximum and as eccentric abrasion due to one side contact is caused. SOLUTION: The cam nose part 24 is formed free to advance and retreat to and from a valve lifter 16 by providing the movable cam 17 to make a suction valve 12 work to open by torque of the camshaft 13 free to move in the diametrical direction through a slot 26 for sliding against the camshaft 13. One end part outer peripheral surface 20c of a mounting portion 20 of the camshaft is formed in a circular arc surface, and one end part inner peripheral surface 26a of the movable cam to be supported on the outer peripheral surface is also formed in a circular arc surface. Additionally, a disconnecting mechanism 19 to connect and fix the movable cam to and on the camshaft or to release connection and fixing in accordance with an engine driving state is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam for opening an intake valve or an exhaust valve, for example, an engine valve of an internal combustion engine for an automobile, against a spring force of a valve spring. The present invention relates to a cam drive control device for a movable cam slidable to a cam.

[0002]

2. Description of the Related Art As a conventional cam drive control device for an internal combustion engine, for example, an actual engine with two intake valves per cylinder is disclosed.
Japanese Patent Application Laid-Open No. -157211 is known.

[0005] Referring to FIG. 17, a schematic description will be given. A camshaft 1 rotating synchronously with a crankshaft and one intake valve or exhaust valve provided on the outer periphery of the camshaft 1 via a valve lifter 3. Raindrop-shaped movable cam 2 to be opened
In the camshaft 1, a mounting section 1 a of the movable cam 2 has a rectangular cross section. On the other hand, in the movable cam 2, a sliding hole 4 having a rectangular cross section is formed in a central portion thereof so as to correspond to the mounting portion 1a of the camshaft 1;
The cam nose portion 2a is slidably supported in the radial direction with respect to the camshaft 1 through the sliding hole 4, and the cam nose portion 2a is movable in the direction of the valve lifter 3 with the sliding.

A cam nose portion 2a of the movable cam 2
Is provided with a support mechanism 6 for supporting the cam nose portion 2a on the camshaft 1 via the fixed cam 5 on the side. Further, a cam nose portion 2a is provided between one end of the mounting portion 1a and an end of the sliding hole 4 on the cam nose portion 2a side.
A push mechanism 7 is provided to push the cam nose portion 2a backward between the other end of the mounting portion 1a and the end of the sliding hole 4 on the base circle 2b side. An urging mechanism 8 is provided.

When the engine is running at a low speed and a low load, the pressing mechanism 7 and the supporting mechanism 6 are not operated, and the movable cam 2 rotates synchronously with the rotation of the cam shaft 1 while the cam nose portion 2 a Retreating against the upper surface,
The intake valve together with the fixed cam 5 controls the valve lift to a low lift.

On the other hand, when the engine shifts to the high engine speed and high load range, the movable cam 2 is fixed to the cam shaft at the maximum advance position of the cam nose portion 2a by the pressing mechanism 7 and the supporting mechanism 6. For this reason, the valve lift of the intake valve is controlled to a high lift, the charging efficiency of the intake air is improved, and the output of the engine can be increased.

[0007]

By the way, in the conventional cam drive control device, the movable cam 2 opposes the two sides 1b, 1c of the mounting portion 1a of the camshaft 1 and the sliding hole 4. Although it moves forward and backward while obtaining sliding contact with both side surfaces 4a and 4b, it is difficult to increase the surface processing accuracy of each surface because each surface is linear, and as a result, Two sides 1 on both sides of the camshaft mounting portion 1a
The width between b and 1c is set to the opposite side surfaces 4 of the sliding hole 4.
a and 4b must be made smaller to some extent, and rattling in the rotating direction between the camshaft mounting portion 1a and the sliding hole 4 is likely to occur, and a tapping sound is likely to occur. .

In particular, when the movable cam 2 further rotates clockwise from the position shown in the figure and rotates while pushing down the upper surface of the valve lifter 3 in the state where the cam nose portion 2a is in the maximum extension state, the reaction force of a valve spring (not shown) causes Sliding hole 4
Of the one side surface 4a, the front end of the one side surface 1b of the mounting portion 1a facing the surface 4a, or the vicinity of the rear end of the other side surface 4b and the rear end of the other side surface 1c of the mounting portion 1a. Is a so-called one-sided contact, so that abrasion easily occurs over time, and as a result, a technical problem such as a decrease in durability is caused.

[0009]

SUMMARY OF THE INVENTION The present invention has been devised in view of the technical problems of the conventional apparatus, and the invention according to claim 1 opens an engine valve by the rotational force of a camshaft. The movable cam is formed with a sliding long hole, and the movable cam can be moved in the radial direction with respect to the camshaft so that the cam nose portion of the movable cam advances and retreats toward the engine valve through the long sliding hole. And a cam drive control device for an internal combustion engine that controls the valve lift of an engine valve by holding the movable cam at an advanced position or switching the movable cam to a retractable position in accordance with an engine operating state. The inner peripheral surface at one end side of the sliding long hole fitted and supported on the camshaft at the position held by the camshaft is formed in an arc shape along the arcuate outer peripheral surface shape of the camshaft, and the cam is formed. At the maximum advanced position of the over's portion with the movable cams provided uncoupling mechanism for connecting or releasing the cam shaft, it is characterized in that a biasing means for biasing the nose portion in the advancing direction.

According to the present invention, the inner peripheral surface of one end of the sliding hole and the outer peripheral surface of the camshaft opposed thereto are arcuate surfaces capable of high machining accuracy, so that the cam nose portion of the movable cam has advanced to the maximum. When the movable cam is rotated, the inner peripheral surface of one end of the sliding hole and the outer peripheral surface of the cam shaft are in contact with each other while the movable cam is rotating. Relative rotation can be restricted. Therefore, it is possible to suppress the occurrence of the backlash or the one-side contact phenomenon due to the rectangular linear surface as in the conventional example.

According to a second aspect of the present invention, when the cam nose portion of the movable cam presses the upper end of the engine valve between the outer peripheral surface of the cam shaft and the sliding elongated hole of the movable cam, Is formed in such a manner as to allow a predetermined amount of rotation with respect to the camshaft in a direction opposite to the camshaft rotation direction.

The invention according to claim 3 is characterized in that a regulating means for regulating the rotation of the movable cam relative to the camshaft in the camshaft rotation direction by a predetermined amount or more is provided.

According to a fourth aspect of the present invention, an inclined surface for urging the movable cam in the rotation direction of the camshaft through the plunger of the urging means is formed at the end of the sliding long hole on the cam nose portion side. The rotation position of the movable cam in the camshaft rotation direction is determined by the inclined surface and the restricting means.

The invention according to claim 5 is characterized in that the movable cam can be connected to the camshaft by the connection releasing mechanism at a position where the movable cam is regulated by the regulating means.

The invention according to claim 6 is characterized in that a fixed cam having a lift portion smaller than the maximum cam lift of the movable cam is provided on a side portion of the movable cam in the camshaft axial direction.

[0016]

1 to 4 show a first embodiment of a cam drive control device for an internal combustion engine according to the present invention. As shown in FIG. The present invention is applied to an internal combustion engine having valves 11 and 12, and one intake valve 11 is opened via a valve lifter 15 by a normal fixed cam 14 fixed to a camshaft 13, while the other is opened. The intake valve 12 side is opened by a cam drive control device.

More specifically, the cam drive control device includes a camshaft 13 disposed above the cylinder head 10 along the engine front-rear direction and driven to rotate by a torque transmitted from a crankshaft; The camshaft 13
A movable cam 17 which is provided on the outer periphery of the camshaft so as to be movable substantially in the radial direction of the camshaft, and which opens and closes the intake valve 12 in cooperation with a valve spring 12a via a closed cylindrical direct-acting valve lifter 16; A support mechanism 18 provided on the outer periphery of the camshaft 13 to support the movable cam 17 in the axial direction, and a connection for connecting the movable cam 17 to the camshaft 13 or releasing the connection from the camshaft 13 according to the engine operating state. A release mechanism 19 and an urging means 27 for urging the movable cam 17 in a direction in which the cam nose portion 24 advances are provided.

The camshaft 13 is supported by a bearing 50 provided at the upper end of the cylinder head 10 so as to be rotatable clockwise (in the direction of the arrow) in FIG. An oil passage 21 to which hydraulic pressure is supplied from a circuit is formed. The camshaft 13 has an attachment portion 20 where the movable cam 17 is located, and has a substantially U-shaped cross section.
c is formed in an arc shape. On the other hand, one side surface 20d in the rotational direction front side on the other end portion 20b side is formed on an inclined surface which is bent inward from a tangent to the plunger axis Y direction described later on the one end portion outer peripheral surface 20c, and the rotational direction rearward. The other side surface 20e is formed substantially linearly by extending a tangent of the arc-shaped outer peripheral surface 20c in the plunger axis Y direction.

The movable cam 17 has a substantially circular base circle portion 23 having a profile formed in a raindrop shape.
And a cam nose portion 24 protruding in a mountain shape on the opposite side of the base circle portion 23, and a flank portion 25 formed between the base circle portion 23 and the cam nose portion 24. The upper surface of the valve lifter 16 is brought into rotary sliding contact. FIG. 12 shows the characteristics of the entire cam profile. Further, the camshaft 1 is provided inside the center of the movable cam 17.
A long sliding hole 26 that engages with the third attachment portion 20 is formed through.

As shown in FIG. 1, the sliding elongated hole 26 is formed in a substantially elliptical shape in the radial direction of the camshaft 13, that is, along the U-shape of the mounting portion 20. The inner peripheral surface 26a of one end of the camshaft 2 is formed in a substantially arc shape along the outer peripheral surface 20c of the camshaft mounting portion 20 in the arc shape.
4 has an inclined surface 26e formed in a downwardly inclined shape from the front end in the rotation direction of the movable cam 17 to the inner peripheral surface 26b of the other end located on the distal end side. Further, both side surfaces 26c and 26d between the inner peripheral surfaces 26a and 26b at the both end portions are formed in parallel and substantially linear.

The movable cam 17 receives a biasing force from the plunger 29 from the inclined surface 26e, and the camshaft 13
It is rotating in the rotation direction.

Accordingly, a triangular gap C having a β angle is formed between the one side face 26c in the rotating direction and the one inclined side face 20d of the mounting portion 20, and the movable cam 17 is formed by the gap C. The mounting portion 20 is allowed to rotate in a direction opposite to the rotation direction of the camshaft 13, and the amount of rotation is reduced when the one side surface 20d comes into contact with the one side surface 26c of the sliding hole 26. The above rotation is regulated. The other side surface 20e of the mounting portion 20 and the other side surface 26d of the sliding hole 26 constitute a restricting means for restricting the rotation of the movable cam 17 in the same direction as the rotation direction of the cam shaft 13 by a predetermined amount or more. .

The movable cam 17 is provided such that the cam nose portion 24 side can move in the protruding (protruding) direction by the urging means 27 through the sliding long hole 26. That is, as shown in FIG. 1, the urging means 27 moves from the center of the other end 20 b of the camshaft attaching portion 20 to the one end 20 b.
A plunger hole 28 drilled along the direction a, and a plunger 29 slidably provided in the plunger hole 28.
And a return spring 30 for urging the plunger 29 in the direction of the inner peripheral surface 26b of the other end of the sliding long hole 26.

The plunger 29 is formed in a cylindrical shape with a lid, and slides in the plunger hole 28 so as to be able to advance and retreat.
The spherical tip surface of the tip portion 29a is in contact with the inclined surface 26e of the sliding long hole 26 on the other end side. The return spring 30 has one end resilient at the bottom of the plunger hole 28 and the other end resilient at the bottom of the inner cavity of the plunger 29.

As shown in FIGS. 3 and 4, the support mechanism 18 includes a pair of first and second flange portions 32, 33 disposed on both sides 17a, 17a of the movable cam 17, and the respective flanges. Internal diametrical direction of the parts 32 and 33 and the camshaft 1
3 and a fixing pin 31 that penetrates in the diametric direction and fixes each of the flange portions 32 and 33 to the camshaft 13.

The flange portions 32 and 33 are formed in a substantially annular shape, and have fitting holes 32c and 33c formed in the center thereof so as to be fitted into the camshaft 13, and have an outer diameter of the base of the movable cam 17. The outer diameter of the circle portion 23 is set to be substantially the same. In addition, the opposing inner surfaces 32a, 3
3a are in sliding contact with both side surfaces of the movable cam 17. further,
When the cam nose portion 24 of the movable cam 17 retreats, the outer peripheral surfaces of the two flange portions 32 and 33 oppose each other on both upper surfaces of the valve lifter 16 with a small clearance with the movable cam 17 interposed therebetween.

As shown in FIGS. 1 and 3, the connection releasing mechanism 19 has a bottomed receiving hole 35 formed in the inner axial direction from the inner end surface 32a toward the outer end surface of the first flange portion 32. A connecting piston 36 slidably provided on the inner end face side from the inside of the receiving hole 35; and a base circle on a center line X connecting the center of the base circle portion 23 of the movable cam 17 to the center of the tip of the cam nose portion 24. A connecting hole 37 formed axially through the portion 23 side and facing the receiving hole 35 on the base circle portion 23 side of the movable cam 17; and one end face slidably provided in the connecting hole 37. A pressing piston 38 which appropriately contacts one end surface of the connecting piston 36,
Toward the outer end of the second flange portion 33,
And a bottomed holding hole 39 formed substantially at the target position, a biasing piston 41 for retracting the connecting piston 36 from the inside thereof through the pressing piston 38 by the spring force of the spring member 40, and the housing hole And a hydraulic circuit 43 for selectively supplying and discharging hydraulic pressure to the bottom of the bottom 35.

A small-diameter air vent 44 is formed in the bottom wall of the holding hole 39 to ensure the free sliding of the urging piston 41.

The axial lengths of the connecting piston 36 and the pressing piston 38 are set substantially equal to the axial lengths of the corresponding receiving holes 35 and the connecting holes 37. The axial length is set shorter than the axial length of the holding hole 39. Further, even when the cam nose portion 24 moves backward to the maximum position, the front and rear end portions of the pressing piston 38 are moved to the opposite inner side surfaces 32a, 33a of the flange portions 32, 33 even when the connecting hole 37 is formed.
It was constituted so that it might become the position which opposes.

The hydraulic circuit 43, as shown in FIG.
An oil hole 45 drilled in the radial direction inside the camshaft 13 and communicating the bottom of the housing hole 35 with the oil passage 21; one end of which communicates with the oil passage 21 and the other end of an oil pump 46;
A hydraulic supply / discharge passage 47 communicating with the oil pump 46
It comprises a two-way type electromagnetic switching valve 48 provided between the oil supply / discharge passage 47 and an orifice 50 provided in a bypass passage 49 which bypasses the electromagnetic switching valve 48.

The electromagnetic switching valve 48 is also connected to a drain passage 51, and is connected to the supply / discharge passage 47 and an oil pump or drain passage 51 by a controller 52 having a built-in computer. Has become. The controller 52 outputs a control signal to the electromagnetic switching valve 48 in accordance with an engine operating state detected by various sensors such as a crank angle sensor, an air flow meter, a water temperature sensor, and a throttle valve opening sensor (not shown). Has become.

In the following, the operation of the present embodiment will be described. First, for example, at the time of low engine speed and low load, the electromagnetic switching valve 48 shuts off the upstream side of the hydraulic supply / discharge passage 47 by a control signal from the controller 52. The hydraulic supply / discharge passage 47 and the drain passage 51 communicate with each other. Therefore, the oil pump oil pressure is not directly supplied to the accommodation hole 35, and the oil pressure reduced by the orifice 50 is supplied only slightly from the bypass passage 49. , Almost no hydraulic pressure is generated.

For this reason, as shown in FIG. 3, the connecting piston 36, the pressing piston 38 and the urging piston 41 are provided in the area of the base circle portion 23 of the movable cam 17 with the respective receiving holes 35, the connecting holes 37 and the holding holes. Although 39 coincide with each other, they are housed and held in the respective accommodation holes 35, the connection holes 37, and the holding holes 39, and the connection between the camshaft 13 and the movable cam 17 is released. I have.

Here, as described above, the reason why the holes 35, 37 and 39 match in the area of the base circle portion 23 is that the contact direction of the plunger 29 with the sliding hole 26 is shown in FIG. Thus, the movable cam 17 receives a moment in the rotational direction of the camshaft 13 by the plunger 29 because the movable cam 17 is inclined by the angle αo with respect to the axis Y of the plunger 29. As a result, the other side surface 26d of the sliding hole 26 serving as the restricting means is formed.
Abuts against the other side surface 20e of the mounting portion 20 to restrict the rotation of the camshaft 13 in the rotation direction.
This is because 5, 37, and 39 are set in advance so as to match.

However, since the movable cam 17 has the sliding hole 26 engaged with the mounting portion 20, the movable cam 17 rotates synchronously with the camshaft 13 clockwise as shown in FIGS. I have.

The movable cam 17 rotated clockwise
Of the valve lifter 16 slides on the upper surface of the valve lifter 16, the flank portion 25 reaches the upper surface of the valve lifter 16 via the base circle portion 23, and the contact position e is
5, the spring force (F) of the valve spring 12a acts on the cam nose portion 24, thereby causing the movable cam 17 to move in the opposite direction to the rotation direction of the cam shaft 13. Directional moment M1
(= F × e) acts. Thereby, the movable cam 17
Starts to rotate relative to the camshaft (phase θ ₁ ) in the direction opposite to the camshaft rotation direction.

A load f (= M1 / l) acts on the tip portion 29a of the plunger 29 due to the moment M1. At this time, since the axial direction Y of the plunger 29 and the direction of the load f (contact direction) are shifted only by a relatively small angle α1, the plunger 29 can be easily pushed back, but the absolute value of the load f is small, so Pushback speed is small.

As a result, the lift of the movable cam 17 is absorbed mainly by the relative rotation of the movable cam 17 in the direction opposite to the rotation direction of the cam shaft 13, and the valve lifter 16 and the intake valve 12 maintain the zero lift while maintaining the zero lift. The smooth operation of the movable cam 17 and the plunger 29 can be obtained.

Thereafter, when the camshaft 13 further rotates (phase θ ₂ ), as shown in FIG.
Comes into contact with the cam nose portion 24, and the gap of the gap C is eliminated by the pressing reaction force from the valve lifter 16, that is, the one side surface 26c of the sliding hole 26 abuts the one side surface 20d of the mounting portion 20. Reverse until regulated. As a result, the movable cam 17 is
3, the phase in the rotation direction is delayed by about β angle with respect to the camshaft 13, and the connection hole 37 is also delayed in phase by approximately β angle with respect to the receiving hole 35.

Also, at this time, the movable cam 17 is slightly pushed back by △ through the sliding hole 26, and the contact position of the cam nose portion 24 with respect to the upper surface of the valve lifter 16 is also moved to the tip end side to e2 Has a relatively large value. Therefore, the moment M acting on the movable cam 17
2 is relatively large, but the moment M2 is received by the contact restriction between the two side surfaces 20d and 26c, and a relatively large load f acts on the plunger 29. Since the axial direction Y of the plunger 29 and the direction of the load f are smaller at an angle α2 and the value of the load f is large, the plunger 29 is smoothly and in opposition to the spring force of the return spring 30. Pushed back at a fast speed.

As a result, the lift of the movable cam 17 is effectively absorbed by the good push-back action of the plunger 29, so that the valve lift of the intake valve 12 is maintained at zero.

Further, when the camshaft 13 is further rotated (phase θ ₃ ), the movable cam 17 is pushed back by the plunger 29 as shown in FIG.
Will be pushed back by the regulatory surface. At this time, since the axial direction Y of the plunger 29 and the direction (contact) of the load f have a small angle (α3), the plunger 29 is pushed back smoothly and at a high speed. Also, the movable cam 17 is pushed back by a large S through the sliding hole 26, and the lift of the movable cam 17 is absorbed at the position shown in FIG. 7 and the valve lift is maintained at zero.

Incidentally, even when the movable cam 17 is largely pushed back in this way, the receiving hole 35 and the holding hole 39 are not
As shown by Z, a part thereof is located on the opposite side surface of the movable cam 17, so that the connecting piston 36 and the urging piston 4
There is no danger of 1 getting out.

When the cam shaft 13 further rotates (phase θ ₄ ) and the tip of the cam nose portion 24 of the movable cam 17 exceeds the upper surface of the valve lifter 16 as shown in FIG. The side surface opposite to the cam nose portion 24 comes into contact with the upper surface of the valve lifter 16, and the lift of the movable cam 17 moves to the flank section. Here, a clearance occurs between the movable cam 17 and the valve lifter 16 due to a click phenomenon, and the plunger 29
At this time, since the contact point of the movable cam 17 with the valve lifter 16 has moved to a point in the opposite direction e4 with respect to the center of the valve lifter 16,
The phase of the movable cam 17 is shifted in the clockwise direction, that is, the rotation direction of the camshaft 13, and a gap C having a δ angle starts to be formed between the two side surfaces 20d and 26c.

Then, when the movable cam 17 further rotates, the lift section of the movable cam 17 is terminated, and the process moves to the base circle section, and finally returns to the state of FIG.
Since the contact direction αo of the plunger 29 is shifted in the rotation direction of the camshaft 13 with respect to the axial direction Y of the plunger 29, the movable cam 17 has the other side surface 26d of the sliding hole 26 formed on the other side surface 20e of the mounting portion 20. The pistons 36, 38, and 41 are stably contacted and regulated, and the axes of the pistons 36, 38, and 41 match.

As described above, in such an engine operation region, the movable cam 17 rotates synchronously with the camshaft 13, but always slides on the upper surface of the valve lifter 16 in a zero-lift state together with the flange portions 32 and 33. , The other intake valve 1
2 is not lifted. Therefore, only one intake valve 11 is lifted by the fixed cam 14 to be opened and closed, and the other intake valve 12 is opened and closed by the valve spring 1.
The valve is closed by the spring force of 2a, which is a so-called valve stop state.

As a result, it is possible to generate a strong swirl in the intake air flowing into the cylinder to promote combustion, thereby improving fuel efficiency.

On the other hand, for example, when the engine speed becomes high and the engine load becomes high, the electromagnetic switching valve 48 is switched based on a control signal output from the controller 52 to shut off the drain passage 51 and simultaneously supply and discharge hydraulic pressure. The upper and lower passages of the passage 47 are communicated. Therefore, the high oil pressure discharged from the oil pump 46 is supplied to the piston housing hole 35 from the oil passage 21 and the oil hole 45 through the oil pressure supply / discharge passage 47.

As a result, the connecting piston 36 is rotated by the movable cam 17 to move the connecting piston 36 to the base circle portion 23 as described above.
At the time when the upper surface faces the upper surface of the valve lifter 16, as shown in FIG.
The leading end of the connecting piston 36 advances by the high oil pressure in the receiving hole 35 against the spring force of the spring member 40, and the pressing piston 38 and the urging piston 41
Is pushed back into the connection hole 37 and the other end of the pressing piston 38 also enters the holding hole 39. Therefore, the movable cam 17 is connected and fixed to the flange portions 32 and 33 with the cam nose portion 24 advanced to the maximum,
It will be connected integrally with the camshaft 13. In addition, the above-mentioned high oil pressure applies a pressing force to the plunger 29 to prevent the movable cam 17 from being exposed to inertial force, and the above-described three holes of the accommodation hole 35, the connection hole 37, and the holding hole 39 match. Is more stable.

Therefore, the movable cam 17 is
4, a cam lift function is exhibited with the rotation of the camshaft 13, and the other intake valve 12 can be made to have a high valve lift (lift L1) as shown in FIG.

As a result, the opening and closing operations of both intake valves 11 and 12 improve the filling efficiency of the intake air and increase the output of the engine.

When the movable cam 17 is connected to the camshaft 13, one end portion 20a
The inner peripheral surface 26a of the arc-shaped one end of the sliding hole 26 is supported in contact with the outer peripheral surface 20c. That is, the movable cam 1 at this time
Since the rotation direction of 7 is regulated by the contact of the arc-shaped inner and outer peripheral surfaces 20c and 26a which can increase the processing accuracy,
The occurrence of backlash between the two can be sufficiently suppressed, the occurrence of hammering noise can be suppressed, and the occurrence of one-sided contact between the two can be suppressed.

The operation of supporting the movable cam 17 will now be described more specifically with reference to FIG.
The contact point P1 of the arc-shaped inner and outer peripheral surfaces 20c, 26a regulates the clockwise rotation of the movable cam 17, and the contact point P2 regulates the counterclockwise rotation of the movable cam 17. The axis of the camshaft 13 is set to O, and the connecting piston 3
Assuming that the axis of 6 is J, the angle formed by OP1-J,
The angles formed by O-P2-J are each substantially 90 °. Therefore, when the camshaft 13 rotates, the movable cam 17 is fixed to the camshaft 13,
As shown in FIG. 11, the valve lifter 16 and the intake valve 12 are lifted by the high lift L1 of the movable cam 17. At this time, as described above, since the regulation of the rotation direction of the movable cam 17 is a highly accurate contact between the arc-shaped inner and outer peripheral surfaces 20c and 26a, occurrence of backlash between the two can be reduced, and the contact surface can be reduced. And the occurrence of one-sided hit can be suppressed. As a result, it is possible to prevent the local surface pressure from increasing, improve the durability of the contact surface, and prevent the occurrence of uneven wear and the like.

Here, the axis J of the connecting piston 36 is
Are located in the projection range of the sliding hole 26 in the longitudinal direction, so that both the clockwise rotation and the counterclockwise rotation of the movable cam 17 are effectively regulated by the inner and outer peripheral surfaces 20c and 26a. be able to. As compared with the case where the axis J is arranged on the side of the movable cam 17, the regulation in both rotational directions is effectively performed.

Further, as described above, at the position where the other side surface 26d of the slide hole 26 comes into contact with the other side surface 20e of the mounting portion 20 to restrict the clockwise rotation of the movable cam 17, each hole 35, Since the 37 and 39 are made to coincide with each other, a quick and reliable disconnection operation of the movable cam 17 with respect to the camshaft 13 can be obtained.

In addition, the connection operation of the connection release means 19, that is, the engagement operation of the connection piston 36 and the pressing piston 38 into the connection holes 37 and the holding holes 39 is performed during the relative rotation of the camshaft 13 and the movable cam 17 described above. In addition to this, in the base circle area of the movable cam 17, that is, in a state where there is no relative rotation, a sufficient connectable time can be secured, so that a stable and more reliable connecting action can be achieved even at a high rotation speed. can get.

According to this embodiment, the urging means 2
7 is provided in the direction in which the cam nose portion 24 of the movable cam 17 advances, so that the cam nose portion 24
When the movable cam 17 is pressed by the spring force of 2a, it is easy to retreat the entire movable cam 17 through the cam nose portion 24.

FIG. 13 shows a second embodiment in which the flanges 32 arranged on both sides or one side of the movable cam 17 are used as low-speed cams. That is, while the height (L1) of the cam nose portion 24 of the movable cam 17 is further increased to set the cam profile for high speed,
The first cam nose portion 24 is provided on the outer periphery of the flange portion 32.
A lower second cam nose portion 64 is formed to set the cam profile for low speed.

Therefore, when the engine is running at a low rotation speed and a low load, the movable cam 17 swings freely, so that when the first cam nose portion 24 reaches the upper surface of the valve lifter 16, the first cam nose portion 24 becomes the same as the second cam nose portion 64 of the flange portion 32. Retreat to the height of. Therefore, in this operation region, the other intake valve 1
The valve 2 operates to open and close according to the lift characteristics of the second cam nose portion 64 without stopping the valve, that is, the low valve lift characteristics of the lift amount L2 as shown by the dashed line in FIG. As a result, the fuel efficiency cannot be improved by the valve stop state, but the combustion can be improved by generating a certain amount of swirl in the cylinder, the engine rotation can be stabilized, and a high torque in a low rotation range can be obtained. On the other hand, when shifting to the high rotation and high load region, the camshaft 13 and the movable cam 17 are integrally connected this time by the connection release means 19, so that the intake valve 12 follows the lift characteristic of the first cam nose portion 24. Opening / closing operation results in high valve lift characteristics with a lift amount L1 as shown by the solid line in FIG. 14, and high output of the engine can be achieved.

FIG. 15 shows a third embodiment, in which a means for regulating the rotation direction of the camshaft 13 of the movable cam 17 is constituted by a plunger 29 and a sliding hole 26.

That is, the other side surface 20e of the mounting portion 20 is formed inwardly in the same manner as the one side surface 20d.
The other side surface 26d of the sliding hole 26 is formed so as to be inclined inward while maintaining a predetermined gap with the other side surface 20e from substantially the center side to the front end side.

Therefore, as shown in the figure, the cam nose 2
When the movable cam 17 attempts to rotate clockwise while the movable plunger 4 is located at the upper position, the biased plunger 29
The upper edge of the inclined other side surface 26d abuts on the end edge of the tip portion 29a of the front end portion 29a to restrict rotation.
Needless to say, it is possible to precisely match 39 with each other, and it is not necessary to form a regulating surface in the mounting portion 20, so that the processing of the camshaft 13 becomes easy.

FIG. 16 shows a fourth embodiment in which the plunger 29 and the other end 26b of the sliding hole 26 are provided as regulating means, and the movable cam 1 of the other end 26b is provided.
7 A surface on the opposite side to the rotation direction of the camshaft 13 from the center line X is formed so as to be inclined upward in the direction of the center line X to form a regulating surface 26.
f, the restricting surface 26f is the tip 2 of the plunger 29.
The camshaft 13 of the movable cam 17 is brought into contact with the edge of 9a.
The rotation in the rotation direction is regulated. And
This restriction angle αo ′ is set substantially equal to the restriction angle αo on the opposite side.

Therefore, according to this embodiment, since the side force of the plunger 29 is canceled and the plunger 29 falls down, the positioning accuracy of the movable cam 17 is improved, and the switching operation of the connection release mechanism 19 is performed. The property becomes good.

The present invention is not limited to the configuration of each of the above-described embodiments. For example, the shape of the cam nose portion 24 or the flank portion 25 on the downside of the valve lift of the movable cam 17 is further changed to lift the movable cam 17. It is also possible to reduce the collision with the valve lifter 16 immediately after the end. In addition, the present device can be applied to both intake valves to perform cylinder stop control and the like.

[0066]

As is apparent from the above description, according to the cam drive control apparatus for an internal combustion engine according to the present invention, the cam nose portion of the movable cam is connected to the camshaft by the connection release mechanism at the position where the cam nose portion has reached the maximum. In the state in which the movable cam is in contact, the inner peripheral surface at one end of the sliding hole is restricted from freely rotating relative to the outer peripheral surface of the camshaft by contact between the arcuate surfaces. Since rotation can be restricted by the possible contact between the arcuate surfaces, the occurrence of backlash between the inner and outer peripheral surfaces is suppressed, and the occurrence of hammering noise can also be prevented.

Further, since the one-sided contact between the inner and outer peripheral surfaces is also suppressed and uneven wear is prevented, the durability can be improved.

According to the second aspect of the present invention, in the state where the cam nose portion of the movable cam is movable forward and backward, the movable cam changes its phase in the direction opposite to the rotation direction of the cam shaft by the gap at the initial stage of the lift of the movable cam. As the lift can be absorbed, the movable cam can be smoothly retracted,
Inadvertent valve lift of the engine valve due to the cam nose can be prevented.

According to the third aspect of the present invention, excessive rotation of the movable cam in the camshaft rotation direction can be restricted in the state where the movable cam can freely advance and retreat. In this case, accurate positioning between the camshaft and the movable cam can be performed, and as a result, the connection and release operations by the connection release mechanism can be stably performed.

According to the fourth aspect of the invention, when the movable cam is movable forward and backward, the positioning of the movable cam with respect to the cam shaft is stabilized by the cooperative action of the inclined surface and the regulating means in the base circle area of the movable cam. As a result, the connection and release operations by the connection release mechanism can be performed more stably.

According to the fifth aspect of the present invention, the connection and release operations by the connection release mechanism can be quickly and reliably performed by restricting the position of the movable cam by the restricting means.

According to the sixth aspect of the present invention, the low lift fixed cam and the high lift movable cam can be arbitrarily switched to perform a variable lift for one engine valve. It is possible to improve engine performance such as fuel efficiency and output torque from the engine to the high rotation range.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing a first embodiment of the present invention.

FIG. 2 is a side view of the embodiment.

FIG. 3 is a sectional view of a main part of the embodiment.

FIG. 4 is a view shown by an arrow B in FIG. 2;

FIG. 5 is an operation explanatory view of a state in which the movable cam can freely move forward and backward in the embodiment.

FIG. 6 is a diagram illustrating the operation of the movable cam according to the embodiment.

FIG. 7 is a diagram illustrating the operation of the movable cam according to the embodiment.

FIG. 8 is a diagram illustrating the operation of the movable cam according to the embodiment.

FIG. 9 is an operation explanatory view showing a connection state by the connection release means of the embodiment.

FIG. 10 is an explanatory view showing a supported state of a connected movable cam.

FIG. 11 is an explanatory view showing a lift state of a movable cam.

FIG. 12 is a valve lift characteristic diagram by the movable cam of the embodiment.

FIG. 13 is a sectional view showing a second embodiment of the present invention.

FIG. 14 is a valve lift characteristic diagram according to the second embodiment.

FIG. 15 is a sectional view showing a third embodiment of the present invention.

FIG. 16 is a cross-sectional view showing a fourth embodiment of the present invention.

FIG. 17 is a sectional view showing a conventional cam drive control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Cylinder head 11, 12 ... Intake valve 13 ... Camshaft 17 ... Movable cam 18 ... Support mechanism 19 ... Disconnection mechanism 20 ... Attachment part 20d ... One side (restriction surface) 20e ... Other side surface (restriction means) 23 ... Base Circle part 24 ... Cam nose part 26 ... Sliding long hole 26a, 26b ... End inner peripheral surface 26d ... Other side surface (restriction means) 27 ... Biasing means 29 ... Plunger

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G018 AB07 BA03 CA01 DA01 DA05 DA18 DA85 EA03 EA04 EA13 EA14 EA35 FA06 FA07 FA11 FA25 GA27 GA32

Claims (6)

[Claims] A movable cam for opening an engine valve by a rotational force of a camshaft;
The movable cam is provided so as to be movable in a radial direction with respect to a camshaft so that a cam nose portion of the movable cam advances and retreats toward the engine valve via the elongated slot for sliding, and the movable cam is brought into an engine operating state. A cam drive control device for an internal combustion engine, which is held at an advanced position or switches to a retractable position to control a valve lift of an engine valve, wherein the cam nose portion is fitted and supported on a camshaft at a position held at the advanced position. The inner peripheral surface on one end side of the sliding long hole is formed in an arc shape along the arc-shaped outer peripheral surface shape of the cam shaft, and the movable cam is connected to or released from the cam shaft at the maximum advance position of the cam nose portion. And a biasing means for biasing the cam nose portion in the advancing direction. 2. When the cam nose portion of the movable cam presses the upper end of the engine valve between the outer peripheral surface of the camshaft and the sliding long hole of the movable cam, the movable cam is moved in the camshaft rotation direction. 2. The cam drive control device for an internal combustion engine according to claim 1, wherein a gap is formed to allow a predetermined amount of rotation with respect to the cam shaft in a reverse direction. 3. The cam drive of an internal combustion engine according to claim 1, further comprising a restricting means for restricting a free rotation of the movable cam relative to the camshaft in a camshaft rotation direction by a predetermined amount or more. Control device. 4. An inclined surface for urging a movable cam in a rotation direction of a camshaft through a plunger of said urging means is formed at an end of said elongated slide hole on a cam nose portion side. 4. The cam drive control device for an internal combustion engine according to claim 3, wherein the rotation position of the movable cam in the camshaft rotation direction is determined by the restricting means. 5. The movable cam can be connected to a camshaft by the connection releasing mechanism at a position where the movable cam is regulated by regulating means.
A cam drive control device for an internal combustion engine according to any one of the above. 6. A fixed cam having a lift portion smaller than a maximum cam lift of the movable cam is provided on a side portion of the movable cam in the camshaft axial direction.
The cam drive control device for an internal combustion engine according to any one of claims 1 to 5,