JP6742793B2 - Internal combustion engine - Google Patents

Description

The present invention relates to internal combustion engines.

In an internal combustion engine, a Miller cycle is known in which the stroke length of the compression stroke is effectively made shorter than the stroke length of the expansion stroke by closing the intake valve at a timing later than the intake bottom dead center in the intake stroke of the cylinder. There is.

The Miller cycle, which has a larger actual expansion ratio than the actual compression ratio, can reduce pumping loss and reduce the amount of exhaust heat to improve thermal efficiency, compared to the Otto cycle in which the actual compression ratio and the actual expansion ratio are substantially equal. It is advantageous in terms.

2. Description of the Related Art Conventionally, as a technique for forming a mirror cycle of an internal combustion engine, there is one that uses a variable valve timing mechanism as described in Patent Document 1. This variable valve timing mechanism has two different intake cams with different cam profiles and different intake valve closing timings, and one of these two intake cams is provided by a hydraulic piston mechanism or the like. It is linked to the rocker arm of the intake valve. An intake cam having a cam profile suitable for the mirror cycle can realize the mirror cycle. An intake cam equipped with a cam profile suitable for the Otto circle can realize the Otto cycle.

JP 2004-183510 JP

The internal combustion engine described in Patent Document 1 is complicated because it is necessary to prepare two types of intake cams having different cam profiles as the opening/closing structure of the intake valve in order to realize each of the Otto cycle and the Miller cycle.

An object of the present invention is to realize an Otto cycle and a Miller cycle in an internal combustion engine while simplifying the opening/closing structure of an intake valve as much as possible.

Invention drives against the intake valve spring force by the intake cam pivotally supported on the camshaft, which opens and closes the intake port by the intake valve, the intake cam relative to the cam shaft according to claim 1 The engagement portion rotatably supported on the cam shaft has an advancing end portion on one end side and an anti-advancing side end portion on the other end side along the cam shaft rotation direction of the idling allowance portion provided on the intake cam. When the cam shaft and the intake shaft are connected to each other, the camshaft and the intake It has a lock part that can be switched between a lock position that locks the cam so that it cannot rotate relative to the lock position and a non-lock position that does not lock it.When the lock part is set to the non-lock position, the intake cam locks the intake valve. Until fully opened, the driving torque of the camshaft pushes the engagement part provided on the camshaft against the end of the intake cam on the advancing side of the idle motion permitting part, and the intake cam fully opens the intake valve. Due to the spring force of the valve, the lead-side end of the idle motion permitting part of the intake cam is separated from the engaging part provided on the cam shaft, and the anti-leading-side end of the idle motion permitting part becomes the engaging part provided on the cam shaft. Until it is pressed, the intake cam is idled with respect to the camshaft in the camshaft rotation direction by an idle angle α, and until the intake cam fully closes the intake valve, the intake cam spring force causes the intake cam to idle. After the end portion of the allowance portion on the non-advancing side is pressed against the engagement portion provided on the cam shaft and the intake cam fully closes the intake valve, the engagement portion provided on the cam shaft is driven by the driving torque of the cam shaft. Until the air cam is separated from the anti-advance side end of the idling allowance part and pressed against the advancing end of the idling allowance part, the camshaft is moved by the idling angle α with respect to the intake cam in the camshaft rotation direction. The intake cam is an internal combustion engine that is configured to idle, and is fixed to the cam shaft so that the intake cam is relatively non-rotatable when the lock part is set to the lock position. When the lock portion is set to the lock position, the engagement portion provided on the camshaft is The intake cam engages with the advancing side end of the idling allowance part, and the lock part provided on the cam shaft engages with the anti-advancing side end of the idling allowance part of the intake cam. The lock portion is fixed so that it cannot rotate relative to the lock shaft, and the lock portion is inserted into a hollow portion provided in the cam shaft so as to be movable in the axial direction of the cam shaft, and the lock position is switched between an unlocked position and a locked position along the axial direction. Inside the spool, with the spool enabled A lock that is loaded in a roll loading portion provided on an outer peripheral wall surrounding an empty portion and alternately engages with a concave portion and a convex portion that are arranged side by side in the axial direction of the spool, and that is inserted into or protruded from the outer peripheral wall of the cam shaft. It has a ball and an actuator for switching the spool between an unlocked position and a locked position, and when the actuator sets the spool to the unlocked position, the lock ball is sunk in the outer peripheral wall of the cam shaft and becomes empty in the intake cam. When the spool is set to the lock position, the lock ball is projected from the outer peripheral wall of the cam shaft and disengages from the anti-advance side end of the intake cam when the spool is set to the lock position. It is adapted to be engaged with .

The invention according to claim 2 is the invention according to claim 1, further comprising: an operating angle θ1 at which the intake cam drives the intake valve when the lock portion is set to the unlocked position, and the lock portion is at the lock position. When set, the intake cam is made smaller than the operating angle θ2 for driving the intake valve by the idling angle α of the engaging portion provided on the cam shaft.

(a) When the lock part is set to the unlocked position, the engaging part provided on the cam shaft pushes the intake cam, and the intake cam opens the intake valve while the intake cam opens. After the valve is fully opened, the intake cam idles in the camshaft rotation direction by the idle angle α. As a result, the working angle θ1 of the intake cam becomes smaller by the above-mentioned idling angle α than when the intake cam does not idle (Miller cycle), and the intake valve closes at an earlier timing. To realize.

When the lock part is set to the lock position and the intake cam does not run idly, the working angle θ2 of the intake cam increases by the above-mentioned idling angle α, and the intake valve closes at a later timing. Realize.

(b) The lock portion is provided on the cam shaft, and the lock portion set to the lock position can be engaged with the end portion on the opposite side of the idle motion permitting portion provided on the intake cam. As a result, when the lock portion is set to the lock position, the engagement portion provided on the cam shaft engages with the leading side end portion of the idle motion allowance portion of the intake cam, and the lock portion provided on the cam shaft causes the intake air to move. The intake cam is securely and easily fixed to the cam shaft so as not to rotate relative to it, by engaging with the end of the cam on the side opposite to the advancing end of the idle motion permitting portion.

(c) When the spool is switched to the locked position or the unlocked position by the actuator, the lock ball that engages with the concave portion or the convex portion of the spool is moved to the anti-advance side end of the idling allowance portion of the intake cam. The part can be easily disengaged or engaged.

FIG. 1 is a schematic diagram showing a valve open/close state in the Otto cycle mode. FIG. 2 is a schematic view showing a valve open/close state in the Otto cycle mode. FIG. 3 is a schematic diagram showing a valve open/close state in the Otto cycle mode. FIG. 4 is a schematic diagram showing a valve open/close state in the Otto cycle mode. FIG. 5 is a schematic view showing a valve open/close state in the Otto cycle mode. FIG. 6 is a schematic diagram showing a valve open/close state in the Miller cycle mode. FIG. 7 is a schematic diagram showing a valve open/close state in the Miller cycle mode. FIG. 8 is a schematic diagram showing a valve open/close state in the Miller cycle mode. FIG. 9 is a schematic diagram showing a valve open/close state in the Miller cycle mode. FIG. 10 is a schematic diagram showing a valve open/close state in the Miller cycle mode. FIG. 11 shows the Otto cycle mode, (A) is a sectional view showing a state before the valve is fully opened, and (B) is a sectional view showing a state after the valve is fully opened. 12A and 12B show the mirror cycle mode. FIG. 12A is a sectional view and FIG. 12B is a sectional view taken along the line BB of FIG. FIG. 13 shows the working angle of the intake cam, (A) is a schematic diagram showing the working angle in the Otto cycle mode, and (B) is a schematic diagram showing the working angle in the Miller cycle mode. FIG. 14 is a valve timing diagram of the exhaust valve and the intake valve.

FIG. 1 shows a main part of an internal combustion engine 10 used in a vehicle or the like according to the present embodiment, which can be operated by switching between Otto cycle mode and Miller cycle mode using natural gas, light oil, gasoline or the like as fuel.

A spark plug (not shown) and a fuel injection valve (not shown) are provided for each cylinder in a cylinder head 11 of the internal combustion engine 10, and an intake port 12 into which intake air flows toward the cylinder and the cylinder concerned. An exhaust port (not shown) through which exhaust gas flows out is provided. The intake port 12 is provided with an intake valve 13 that opens and closes it, and the exhaust port is provided with an exhaust valve (not shown) that opens and closes it.

Hereinafter, the opening/closing structure of the intake valve 13 will be described in detail.
The internal combustion engine 10 of the present embodiment has a cam shaft 20 to which a driving torque generated from a crank shaft is transmitted, and an intake cam 30 pivotally supported by the cam shaft 20 resists the spring force of the valve spring 40. Then, the intake valve 13 is driven, and the intake port 12 is opened and closed by the intake valve 13. The intake valve 13 is attached in a direction in which the intake port 12 is closed by the spring force of a valve spring 40 interposed between the valve spring retainer 41 attached to the valve stem 13A and the upper surface of the cylinder head 11. It is energized.

Here, as shown in FIG. 11, the intake cam 30 is rotatably supported by the cam shaft 20 so that the engagement portion 50 provided on the cam shaft 20 can move the engaging portion 50 provided on the intake cam 30. Is allowed to move in the idling range R which is sandwiched between the advancing side end portion 31A on one end side and the anti-advancing side end portion 31B on the other end side along the camshaft rotation direction N.

The camshaft 20 is hollow and has a semi-arcuate shape that is provided at a single circumferential position in a cross section perpendicular to the axis of the cylindrical outer peripheral wall 21 that surrounds the hollow portion H and expands outward in the radial direction. The groove 22 extends in the axial direction, and a part (substantially half cross section) of the arc-shaped cross section of the round bar-shaped engaging portion 50 is fitted into the semi-arc shape groove 22, and the arc-shaped cross section of the engaging portion 50. The remaining part of the above is projected outward from the cylindrical outer peripheral wall 21 of the cam shaft 20.

Further, the intake cam 30 is provided with a hollow motion permitting portion 31 which is recessed on the inner peripheral surface of the cam shaft 20 which is fitted to the cylindrical outer peripheral wall 21 so as to be relatively rotatable. The idling allowance portion 31 faces the outer peripheral surface of the cylindrical outer peripheral wall 21 of the cam shaft 20 and extends over the above-mentioned idle movable range R along the circumferential direction of the outer peripheral surface. On the groove surface between the advancing side end portion 31A and the anti-advancing side end portion 31B of the idle motion allowing portion 31, the engaging portion 50 protruding from the cylindrical outer peripheral wall 21 of the cam shaft 20 slides through a minute gap. The groove surfaces of the advancing side end portion 31A and the anti-advancing side end portion 31B have contactable groove depths, and the engaging portions 50 projecting from the cylindrical outer peripheral wall 21 of the camshaft 20 are brought into pressure contact with and engaged with each other. Make an arc shape to get.

Further, in the internal combustion engine 10, the engagement portion 50 provided on the cam shaft 20 is engaged with the advance side end portion 31A of the idling allowance portion 31 provided on the intake cam 30, and the cam shaft 20 and the intake cam 30 are provided. It has a lock portion 60 that can be set to be switched between a locked position (Fig. 12(A)) that locks and are locked so that they cannot rotate relative to each other and an unlocked position (Fig. 11(A)) that does not lock them.

In the present embodiment, as shown in FIG. 12, the lock portion 60 is configured to have a spool 61, a lock ball 62, and an actuator 63. The spool 61 is inserted into a hollow portion H provided in the cam shaft 20 to be movable in the axial direction of the cam shaft 20, and has an unlocked position (FIG. 11) and a locked position (FIG. 12) along the axial direction. It can be set to switch to. The lock balls 62 are loaded in the ball loading portion 23 provided on the cylindrical outer peripheral wall 21 surrounding the hollow portion H of the cam shaft 20, and are alternately arranged in the concave portions 61A and the convex portions 61B arranged side by side in the axial direction of the spool 61. It engages and it immerses in (FIG. 11) or protrudes (FIG. 12) in and out of the cylindrical outer peripheral wall 21 of the camshaft 20. In the present embodiment, hole-shaped ball loading portions 23 are loaded at each of three positions along the axial direction of the cylindrical outer peripheral wall 21 of the cam shaft 20, and a plurality of (three in this embodiment) lock balls 62 are provided. Each is loaded in the ball loading unit 23. Accordingly, the spool 61 is provided with three sets of an annular recess 61A and an annular protrusion 61B, which are aligned in the axial direction of the spool 61, in the axial direction. The actuator 63 axially reciprocates the spool 61 by electric power (electrical force or the like) or fluid pressure (hydraulic pressure or the like) to switch the spool 61 between an unlocked position and a locked position. Therefore, in the lock portion 60, when the actuator 63 sets the spool 61 to the unlocked position (FIG. 11 ), the lock ball 62 is sunk in the cylindrical outer peripheral wall 21 of the cam shaft 20, and the idling allowance portion 31 of the intake cam 30. It is disengaged from the anti-advance side end portion 31B. On the other hand, when the actuator 63 sets the spool 61 to the lock position (FIG. 12 ), the lock ball 62 is projected from the cylindrical outer peripheral wall 21 of the cam shaft 20, and the end of the intake cam 30 on the side opposite to the advancing side of the idling allowance portion 31. The portion 31B is engaged.

However, in (A) the internal combustion engine 10, when the lock portion 60 (lock ball 62) is set to the unlocked position by the actuator 63 (Otto cycle mode) (FIG. 11),
i. Until the intake cam 30 fully opens the intake valve 13 (the intake cam 30 presses the upslope surface from the basic circle of the profile to the top in the rotational direction N to the valve stem 13A), the cam shaft 20 is driven to rotate. By this, the engaging portion 50 provided on the cam shaft 20 is pressed against the leading side end portion 31A of the idle motion allowing portion 31 of the intake cam 30,
ii. The valve spring in the intake valve 13 after the intake cam 30 fully opens the intake valve 13 (the intake cam 30 presses the downward slope surface from the top of the profile to the basic circle in the rotation direction N to the valve stem 13A). By the spring force of 40, the advancing side end 31A of the idling allowance portion 31 of the intake cam 30 is separated from the engaging portion 50 provided on the cam shaft 20, and the anti-advancing side end 31B of the idling allowance portion 31 is cammed. Until the intake cam 30 is pressed against the engaging portion 50 provided on the shaft 20, the intake cam 30 is made to idle with respect to the cam shaft 20 in the cam shaft rotation direction N by an idle angle α.
iii. Until the intake cam 30 fully closes the intake valve 13 (the intake cam 30 presses the basic circle of the profile against the valve stem 13A in the rotation direction N), the intake cam 30 is pressed by the spring force of the valve spring 40 in the intake valve 13. The anti-advance side end portion 31B of the idling allowance portion 31 is pressed against the engaging portion 50 provided on the cam shaft 20,
iv. After the intake cam 30 fully closes the intake valve 13 (the intake cam 30 presses the basic circle of the profile against the valve stem 13A in the rotation direction N), the camshaft 20 is driven by the driving torque of the camshaft 20. The camshaft 20 until the engaging portion 50 provided in the intake cam 30 is separated from the anti-advance side end portion 31B of the idling allowance portion 31 of the intake cam 30 and is pressed against the advancing side end portion 31A of the idling allowance portion 31. The cam 30 is made to idle by the idle angle α in the camshaft rotation direction N.

In the above iv, the engaging portion 50 provided on the cam shaft 20 is separated from the anti-advance side end portion 31B of the idling allowance portion 31 of the intake cam 30 and pushed to the advancing side end portion 31A of the idle allowance portion 31. As the force to be applied to the intake cam 30 so as to apply, in addition to the driving rotational force of the cam shaft 20, a spring force of a return spring formed of a torsion coil spring or the like interposed between the cam shaft 20 and the intake cam 30. May be used. The spring force of the return spring causes the intake cam 30 to rotate with respect to the cam shaft 20 in the direction opposite to the cam shaft rotation direction N.

On the other hand, (B) When the lock portion 60 (lock ball 62) is set to the lock position by the actuator 63 (mirror cycle mode) (FIG. 12), the engaging portion 50 provided on the cam shaft 20 causes the empty portion of the intake cam 30 to move. The lock portion 60 (lock ball 62) provided on the camshaft 20 is engaged with the lead-side end portion 31A of the motion permitting portion 31, and is engaged with the anti-lead end portion 31B of the air-moving permitting portion 31 of the intake cam 30. The intake cam 30 is fixed to the cam shaft 20 so as not to rotate relative to it.

FIG. 13 shows an operating angle θ1 (FIG. 13A) at which the intake cam 30 drives the intake valve 13 when the lock portion 60 (lock ball 62) is set to the unlocked position (Otto cycle mode), and When the portion 60 (lock ball 62) is set to the lock position (mirror cycle mode), the operating angle θ2 (FIG. 13B) at which the intake cam 30 drives the intake valve 13 is shown in comparison. is there. In the profile of the intake cam 30 that is not idling (solid line), a indicates a boundary point between the basic circle and the upward slope surface, b indicates a top portion, and c indicates a boundary point between the basic circle and the downward slope surface. In the profile (two-dot chain line) of the intake cam 30 after idling due to the spring force F of the valve spring 40, b'denotes a top portion and c'denotes a boundary point between the base circle and the descending slope surface. o indicates the center point of the intake cam 30. As is clear from FIG. 13, the operating angle θ1 (∠aoc′) at which the intake cam 30 drives the intake valve 13 when the lock portion 60 (lock ball 62) is set to the unlocked position is equal to the lock portion 60 (lock As shown in FIG. 13, the engagement portion 50 provided on the cam shaft 20 is more than the working angle θ2 (∠aoc) at which the intake cam 30 drives the intake valve 13 when the ball 62) is set to the lock position. It is smaller by the aerodynamic angle α.

Therefore, as shown in FIG. 14, the intake valve 13 has the valve timing A (Otto cycle mode) at which the lock portion 60 is set at the unlocked position and the lock portion 60 is set at the locked position. The valve timing B (Miller cycle mode) is closed earlier than the closing timing by the above-mentioned aerodynamic angle α. In other words, the valve closing timing of the valve timing B in the Miller cycle mode is later than the valve closing timing of the valve timing A in the Otto cycle mode by the above-mentioned idling angle α.

Therefore, the ECU (control means) 70 of the internal combustion engine 10 needs to have an Otto cycle based on the detection results of the engine speed sensor, the accelerator position sensor, the vehicle speed sensor, etc., for example, when the engine operating state is in the low speed range. If so, the ECU 70 controls the actuator 63 to set the lock portion 60 (lock ball 62) to the unlocked position, and sets the valve timing of the intake valve 13 to the Otto cycle mode. On the other hand, when it is determined that the mirror cycle is necessary because the engine operating state is in the medium-high speed range, the ECU 70 controls the actuator 63 to set the lock portion 60 (lock ball 62) to the lock position, The valve timing of the intake valve 13 is set to the Miller cycle mode.

Hereinafter, the Otto cycle mode and the Miller cycle mode will be described in detail.
(A) Otto cycle mode (Figs. 1 to 5)
The actuator 63 sets the lock portion 60 (lock ball 62) to the unlocked position (FIG. 11).

(1) Until the intake cam 30 fully opens the intake valve 13 from the fully closed state, as shown in FIGS. 1 and 2, the cam shaft 20 that receives the driving rotational force is the engaging portion 50 provided on the cam shaft 20. Of the intake cam 30 is pressed against the advancing side end portion 31A of the idling allowance portion 31 of the intake cam 30, and the intake cam 30 is rotated. The valve stem 13A is pushed down against and the intake valve 13 is opened.

(2) After the intake cam 30 fully opens the intake valve 13, as shown in FIGS. 3 and 4, the valve stem 13A, which receives the spring force of the valve spring 40, moves from the top of the profile of the intake cam 30 to the basic circle. Is pressed against the descending slope surface in the camshaft rotation direction N to separate the leading end 31A of the idle motion permitting portion 31 of the intake camshaft 30 from the engaging portion 50 provided on the camshaft 20. The intake cam 30 is idly moved in the camshaft rotation direction N by the idling angle α with respect to the camshaft 20 until the anti-advance side end 31B of the shaft 31 is pressed against the engaging portion 50 provided on the camshaft 20.

(3) After the idling of the intake cam 30, until the intake cam 30 fully closes the intake valve 13, the valve stem 13A receiving the spring force of the valve spring 40 cams the downward slope surface of the profile of the intake cam 30. Under pressure in the axial rotation direction N, the anti-advance side end portion 31B of the idling allowance portion 31 of the intake camshaft 30 is pressed against the engaging portion 50 provided on the camshaft 20. The intake cam 30 rotates with the cam shaft 20 so as to follow the cam shaft 20 while pressing the anti-advance side end 31B of the idling allowance part 31 against the engaging part 50 provided on the cam shaft 20. Close.

(4) After the intake cam 30 fully closes the intake valve 13, the cam shaft 20 that receives the driving rotational force moves the engaging portion 50 provided on the cam shaft 20 to the idling allowance portion 31 of the intake cam 30. Until the end 31A of the anti-advance side is separated and the end 31A of the idling allowance portion 31 is pressed, the camshaft 20 is idly moved in the camshaft rotation direction N relative to the intake cam 30 by an idling angle α. Let As a result, the process returns to the initial stage of starting opening the intake valve 13 in (1) above.

(B) Miller cycle mode (FIGS. 6 to 10)
The lock portion 60 (lock ball 62) is set to the lock position by the actuator 63, and the intake cam 30 is fixed to the cam shaft 20 so as not to rotate relative to it (FIG. 12).

(1) Until the intake cam 30 fully opens the intake valve 13 from the fully closed state, as shown in FIGS. 6 and 7, the cam shaft 20 which receives the driving rotational force rotates the intake cam 30, and the intake cam 30 The upward slope surface from the basic circle of the profile to the top of the profile pushes down the valve stem 13A against the spring force of the valve spring 40 to open the intake valve 13.

(2) From the time when the intake cam 30 fully opens the intake valve 13 to the time when the intake valve 13 is fully closed, as shown in FIGS. 8 to 10, the valve stem 13A that receives the spring force of the valve spring 40 has the profile of the intake cam 30. The intake camshaft 30 rotates together with the camshaft 20 so as to follow the camshaft 20 under the condition that the downward slope surface from the top to the base circle is pressed in the camshaft rotation direction N, and the intake valve 13 is closed.

(3) After the intake cam 30 fully closes the intake valve 13, the camshaft 20 that receives the driving rotational force rotates the intake cam 30 and returns to the initial stage where the intake valve 13 starts to open in (1) above. ..

According to this embodiment, the following operational effects are obtained.
(a) A process in which the engagement portion 50 provided on the camshaft 20 pushes the intake cam 30 when the lock portion 60 is set to the unlocked position, and the intake cam 30 operates to open the intake valve 13. Then, after the intake cam 30 fully opens the intake valve 13, the intake cam 30 idles in the camshaft rotation direction by the idle angle α. As a result, the working angle θ1 of the intake cam 30 becomes smaller by the aerodynamic angle α as compared with the case where the intake cam 30 does not move (Miller cycle), and the intake valve 13 closes at an earlier timing. Realize the Otto cycle.

When the lock portion 60 is set to the lock position and the intake cam 30 does not idle, the working angle θ2 of the intake cam 30 increases by the idle angle α and the intake valve 13 closes at a later timing. Realize the mirror cycle.

(b) The lock portion 60 is provided on the cam shaft 20, and the lock portion 60 set at the lock position can be engaged with the anti-advance side end portion 31B of the idling allowance portion 31 provided on the intake cam 30. .. As a result, when the lock portion 60 is set to the lock position, the engagement portion 50 provided on the cam shaft 20 engages with the advance side end portion 31A of the idling allowance portion 31 of the intake cam 30 and the cam shaft 20 The lock portion 60 provided at the end engages with the anti-advance side end portion 31B of the idling allowance portion 31 of the intake cam 30, and the intake cam 30 is securely and easily fixed to the cam shaft 20 so as not to be relatively rotatable.

(c) When the spool 61 is switched to the locked position or the unlocked position by the actuator 63, the lock ball 62, which is engaged with the concave portion 61A or the convex portion 61B of the spool 61, is moved in the idle cam of the intake cam 30. It is possible to easily disengage or engage the end portion 31B on the opposite side of the allowance portion 31.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the scope of the present invention. Included in the present invention. For example, in the present invention, the lock portion relatively rotates the cam shaft and the intake cam under the condition that the engagement portion provided on the cam shaft engages with the advance side end portion of the idling allowance portion provided on the intake cam. It suffices as long as it can be set to be locked between a lock position where it cannot be fixed and a non-lock position where it is not fixed. It doesn't have to be one.

Further, in the present invention, the intake cam is not limited to one that directly drives the valve stem of the intake valve, but may be one that drives the valve stem of the intake valve via a rocker arm or the like.

According to the present invention, an Otto cycle and a Miller cycle can be realized in an internal combustion engine while simplifying the intake valve opening/closing structure as much as possible.

10 Internal Combustion Engine 12 Intake Port 13 Intake Valve 20 Camshaft 21 Outer Wall 23 Ball Loading Part 30 Intake Cam 31 Air Motion Allowable Part 31A Advance Side End 31B Anti-Advance Side End 40 Valve Spring 50 Engagement Part 60 Lock Part 61 Spool 61A concave portion 61B convex portion 62 lock ball 63 actuator

Claims (2)

The intake valve driving against the spring force by the pivoted intake cam on the camshaft, which opens and closes the intake port by the intake valve,
The intake cam is rotatably supported on the cam shaft, and the engaging portion provided on the cam shaft has an advancing end on the one end side and the other end along the cam shaft rotation direction of the idling allowance portion provided on the intake cam. It is possible to run idly within the range of idling that is sandwiched between the opposite end side of the side and
Under the condition that the engaging portion provided on the cam shaft engages with the leading end of the idling allowance portion provided on the intake cam, the cam shaft and the intake cam are locked so as not to rotate relative to each other, and not locked. Has a lock part that can be set to switch to the unlocked position,
When the lock part is set to the unlocked position, the engagement part provided on the camshaft by the driving torque of the camshaft until the intake cam fully opens the intake valve causes the leading end of the idle motion allowance part of the intake cam. When the intake cam is pressed against the air intake valve and the intake valve is fully opened, the spring force of the intake valve causes the advancing end of the idle cam of the intake cam to move away from the engagement part provided on the cam shaft. The intake cam is made to idle by an idling angle α in the camshaft rotation direction with respect to the camshaft until the end of the allowance portion on the opposite side is pressed against the engagement portion provided on the camshaft. Until the valve is fully closed, the spring force of the intake valve pushes the end of the intake cam on the non-advance side of the idle motion allowance part against the engaging part provided on the cam shaft, and the intake cam fully closes the intake valve. Until the engaging portion provided on the cam shaft is separated from the anti-advance side end portion of the idle motion permitting portion of the intake cam by the driving torque of the cam shaft, and is pressed to the advance side end portion of the idle motion permitting portion. The camshaft is configured to idle relative to the intake cam in the camshaft rotation direction by an idle angle α,
When the lock portion is set to the lock position, the intake cam is an internal combustion engine that is fixed to the cam shaft so that it cannot rotate relative to the cam shaft .
The lock portion is provided on the cam shaft, and the lock portion set to the lock position is engageable with the end portion on the side opposite to the advancing end of the idle motion permitting portion provided on the intake cam,
When the lock portion is set to the lock position, the engagement portion provided on the cam shaft engages with the leading side end portion of the idling allowance portion of the intake cam, and the lock portion provided on the cam shaft moves to the empty portion of the intake cam. The intake cam is fixed to the cam shaft so as not to rotate relative to it, by engaging the opposite end of the motion permitting part.
The lock is
A spool which is inserted into a hollow portion provided in the cam shaft and is movable in the axial direction of the cam shaft, and which can be set to be switched between an unlocked position and a locked position along the axial direction,
It is loaded in a roll loading portion provided on the outer peripheral wall surrounding the hollow portion of the cam shaft, and alternately engages with the concave portion and the convex portion arranged in parallel in the axial direction of the spool, and sinks into or out of the outer peripheral wall of the cam shaft. With a protruding rock ball,
An actuator for switching the spool between an unlocked position and a locked position,
When the actuator sets the spool to the unlocked position, the lock ball is retracted into the outer peripheral wall of the cam shaft and disengaged from the end of the intake cam on the non-advancing side of the idle motion allowing part, and the spool is set to the locked position. At this time, the lock ball projects from the outer peripheral wall of the cam shaft and is engaged with the end of the intake cam on the side opposite to the advancing end of the idling allowance portion . The operating angle θ1 at which the intake cam drives the intake valve when the lock portion is set to the unlocked position is greater than the operating angle θ2 at which the intake cam drives the intake valve when the lock portion is set to the lock position. Also, the internal combustion engine according to claim 1, wherein the engagement portion provided on the cam shaft is smaller by the idling angle α.

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