Continuous variable valve duration apparatus and engine provided with the same

A continuous variable valve duration system may include a camshaft, a first cam portion including a first cam, of which the camshaft is inserted therein, an internal bracket transmitting rotation of the camshaft to the first cam portion, a control shaft parallel to the camshaft, a slider housing in which the internal bracket is rotatably inserted, on which a control groove where the control shaft is inserted into is formed, and the slider housing movable vertical to the camshaft, a guider configured for guiding movement of the slider housing, a rocker shaft, a first rocker arm rotatably disposed to the rocker shaft of which a first end portion contacts with the first cam and of which a second end portion is connected to a first valve and a control portion selectively rotating the control shaft for changing a position of the slider housing.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2016-0169855 filed on Dec. 13, 2016, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a continuous variable valve duration system and an engine provided with the same. More particularly, the present invention relates to a continuous variable valve duration system an engine provided with the same which may vary opening duration of a valve according to operation conditions of an engine with a simple construction.

Description of Related Art

An internal combustion engine generates power by burning fuel in a combustion chamber in an air media drawn into the chamber. Intake valves are operated by a camshaft in order to intake the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and a combustion gas is exhausted from the combustion chamber while the exhaust valves are open.

Optimal operation of the intake valves and the exhaust valves depends on a rotation speed of the engine. That is, an optimal lift or optimal opening or closing timing of the valves depends on the rotation speed of the engine. In order to achieve such optimal valve operation depending on the rotation speed of the engine, various researches, such as designing of a plurality of cams and a continuous variable valve lift (CVVL) that can change valve lift according to engine speed, have been undertaken.

Also, in order to achieve such an optimal valve operation depending on the rotation speed of the engine, research has been undertaken on a continuously variable valve timing (CVVT) apparatus that enables different valve timing operations depending on the engine speed. The general CVVT may change valve timing with a fixed valve opening duration.

However, the general CVVL and CVVT are complicated in construction and are expensive in manufacturing cost.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a continuous variable valve duration system and an engine provided with the same which may vary opening duration of a valve according to operation conditions of an engine, with a simple construction.

A continuous variable valve duration system according to aspects of the present invention may be applied to a Single OverHead Cam (SOHC) engine to reduce weight of the engine and driving resistance.

A continuous variable valve duration system according to an exemplary embodiment of the present invention may include a camshaft, a first cam portion including a first cam, of which the camshaft is inserted therein and of which a relative phase angle of the first cam with respect to the camshaft is configured to be variable, an internal bracket configured for transmitting a rotation of the camshaft to the first cam portion, a control shaft parallel to the camshaft, a slider housing in which the internal bracket is rotatably inserted, on which a control groove where the control shaft is inserted into is formed, and the slider housing movable vertical to the camshaft, a guider configured for guiding a movement of the slider housing, a rocker shaft, a first rocker arm rotatably disposed to the rocker shaft of which a first end portion is configured to contact with the first cam and of which a second end portion is connected to a first valve and a control portion configured for selectively rotating the control shaft for changing a position of the slider housing.

The continuous variable valve duration system may further include an eccentric rod connected the control shaft and inserted into the control groove.

A guide hole may be formed at the slider housing and the guider may include a guide shaft inserted into the guide hole and guiding movement of the slider housing and a guide shaft support portion configured for supporting the guide shaft.

At least one guide shaft may be disposed.

A first slot and a second slot may be formed at the internal bracket and the continuous variable valve duration system may further include a first slider pin slidably connected to the camshaft and rotatably inserted into the first slot and a second slider pin on which a pin slot is formed and rotatably inserted into the second slot.

The first slider pin may include a pin body slidably connected to the camshaft along a longitudinal direction thereof and a pin head inserted into the first slot.

The first cam portion may further include an external shaft on which a wheel key inserted into the pin slot is formed and of which the camshaft is inserted, and to which the first cam is connected.

The continuous variable valve duration system may further include a first bridge connected to the second end portion of the first rocker arm, and two first valves may be connected to the first bridge.

The continuous variable valve duration system may further include a second cam portion including a second cam rotating with the camshaft and a second rocker arm rotatably connected to the rocker shaft, of which a first end portion contacts with the second cam and of which a second end portion is connected to a second valve.

The continuous variable valve duration system may further include a second bridge connected to the second end portion of the second rocker arm, and two second valves may be connected to the second bridge.

The first cam portion may further include an external shaft on which a wheel key inserted into the pin slot is formed, of which the camshaft is inserted, on which guide slot is formed along a circumferential direction and the external shaft to which the first cam is connected.

The continuous variable valve duration system may further include a first bridge connected to the second end portion of the first rocker arm, and two first valves may be connected to the first bridge.

The continuous variable valve duration system may further include a second cam portion including a second cam connected to the camshaft through the guide slot and a second rocker arm rotatably connected to the rocker shaft, of which a first end portion contacts with the second cam and of which a second end portion is connected to a second valve.

The continuous variable valve duration system may further include a second bridge connected to the second end portion of the second rocker arm, and two second valves may be connected to the second bridge.

The continuous variable valve duration system may further include a support on which a control shaft supporting portion configured for rotatably supporting the control shaft is formed.

The guide shaft support portion may be integrally formed with the support.

The continuous variable valve duration system may further include a cam cap configured for rotatably supporting the camshaft.

A rocker shaft supporting portion configured for supporting the rocker shaft may be formed at the cam cap.

The support may be connected to the cam cap.

The continuous variable valve duration system may further include a bearing disposed between the internal bracket and the slider housing.

An engine according to an exemplary embodiment of the present invention may be provided with the continuous variable valve duration system.

As described above, a continuous variable valve duration system according to an exemplary embodiment of the present invention may vary an opening duration of a valve according to operation conditions of an engine, with a simple construction.

The continuous variable valve duration system according to an exemplary embodiment of the present invention may be reduced in size and thus an entire height of a valve train may be reduced.

Since the continuous variable valve duration system may be applied to a conventional engine without excessive modification, thus productivity may be enhance and production cost may be reduced.

Also, since the slider housing moves along a horizontal direction of an engine, thus instability or noise due to vertical direction load of a cam may be suppressed.

DETAILED DESCRIPTION

In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration.

A part irrelevant to the description will be omitted to clearly describe the present invention, and the same or similar elements will be designated by the same reference numerals throughout the specification.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.

Throughout the specification and the claims, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

FIG. 1is a perspective view of an engine provided with a continuous variable valve duration system according to an exemplary embodiment of the present invention andFIG. 2is a perspective view of a continuous variable valve duration system according to an exemplary embodiment of the present invention.

FIG. 3is a partial exploded perspective view of a slider housing of a continuous variable valve duration system according to an exemplary embodiment of the present invention andFIG. 4is an exploded perspective view of a slider housing of a continuous variable valve duration system according to an exemplary embodiment of the present invention.

FIG. 5is a drawing showing a first and a second cam portion of a continuous variable valve duration system according to an exemplary embodiment of the present invention.

Referring toFIG. 1toFIG. 5, an engine10according to an exemplary embodiment of the present invention is provided with a continuous variable valve duration system.

The continuous variable valve duration system according to an exemplary embodiment of the present invention may include a camshaft30, a first cam portion40including a first cam42, of which the camshaft is30inserted therein and of which relative phase angle of the first cam42with respect to the camshaft30is variable, an internal bracket20transmitting rotation of the camshaft30to the first cam portion40, a control shaft102parallel to the camshaft30, a slider housing90in which the internal bracket20is rotatably inserted, on which a control groove92where the control shaft102is inserted into is formed, and the slider housing90movable vertical to the camshaft30, a guider97configured for guiding movement of the slider housing90, a rocker shaft60, a first rocker arm70rotatably disposed to the rocker shaft60of which a first end portion contacts with the first cam42and of which a second end portion is connected to a first valve72and a control portion100selectively rotating the control shaft102for changing a position of the slider housing90.

An eccentric rod106is connected to the control shaft102and inserted into the control groove92and the eccentric rod106is eccentrically connected to the control shaft102.

A guide hole96is formed at the slider housing90and the guider97includes a guide shaft98inserted into the guide hole96and guiding movement of the slider housing90and a guide shaft support portion99supporting the guide shaft98.

At least one guide shaft98may be disposed.

That is, with one guide shaft element numbers may be reduced, and as shown in drawings, two or more guide shafts98may be disposed for stably guiding movement of the slider housing90.

Due to manufacturing tolerance vibration or noise of the slider housing90generated, however two or more guide shafts may induce stable movement of the slider housing90and may suppress noise and vibration of the slider housing90.

The control portion100includes control motor104selectively rotating the control shaft102and a gear, a worm gear, a planetary gear and so on may be interposed between the control shaft102and the control motor104for reducing motor capacity.

The continuous variable valve duration system may further include a support12on which a control shaft supporting portion13rotatably supporting the control shaft102is formed.

The guide shaft support portion99and the support12may be integrally formed to reduce element numbers.

The continuous variable valve duration system may further include a cam cap120on which a camshaft supporting portion15rotatably supporting the camshaft30is formed.

A camshaft bearing36is connected to the camshaft30and mounted to the camshaft supporting portion15.

A rocker shaft supporting portion17supporting the rocker shaft60is formed at the cam cap120.

The support12may be connected to the cam cap120for simplifying engine layout.

A first slot22and a second slot23are formed at the internal bracket20.

The continuous variable valve duration system further includes a first slider pin24slidably connected to the camshaft30and rotatably inserted into the first slot22and a second slider pin28on which a pin slot29is formed and rotatably inserted into the second slot23.

The first slider pin24includes a pin body25slidably connected to the camshaft30along a longitudinal direction thereof and a pin head26inserted into the first slot22. And a camshaft hole32is formed at the camshaft30and the pin body25is slidably inserted into the camshaft hole32.

The first cam portion40further includes an external shaft43on which a wheel key45inserted into the pin slot29is formed, of which the camshaft30is inserted, and to which the first cam42is connected.

A first roller76contacting the first cam42is connected to the first end portion of the first rocker arm70and the first roller76is connected to the first bridge74through a roller pin77.

A first bridge74is connected to the second end portion of the first rocker arm70and two first valves72is connected to the first bridge74.

The continuous variable valve duration system further includes a second cam portion50including a second cam52rotating with the camshaft30and a second rocker arm80rotatably connected to the rocker shaft60, of which a first end portion contacts with the second cam52and of which a second end portion is connected to a second valve82.

A second roller86contacting the second cam52is connected to the first end portion of the second rocker arm80and the second roller86is connected to the second bridge84through a roller pin87.

A second bridge84is connected to the second end portion of the second rocker arm80and two second valves82may be connected to the second bridge80.

A first rocker arm hole78is formed at the first rocker arm70, a second rocker arm hole88is formed at the second rocker arm80and the rocker shaft60is inserted into the first rocker arm hole78and the second rocker arm hole88.

A guide slot44is formed at the external shaft43along circumferential direction and the second cam portion55is connected to the camshaft30through the guide slot44.

A cam connecting hole34is formed at the camshaft30, a cam hole54is formed at the second cam portion50, a cam connecting pin56is inserted into the cam connecting hole34and the cam hole54and the guide slot44guides relative rotation of the cam connecting pin56.

A bearing94is disposed between the internal bracket20and the slider housing90for rotatably supporting the internal bracket20.

FIG. 6andFIG. 7are drawings showing operation of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention.FIG. 8andFIG. 9are drawings showing mechanical motions of cams of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention.

Referring toFIG. 1toFIG. 9, operations of the continuous variable valve duration system according to various aspects of the present invention will be discussed.

As shown inFIG. 6, in the case that rotation centers of the camshaft30and the internal bracket20are coincident, the first cam42rotates with the same phase angle of the camshaft30.

As shown inFIG. 7, when the control portion100is operated to rotate the control shaft102, the eccentric rod106moves the slider housing90along a longitudinal direction of the guide shaft98.

When a rotation center X of the camshaft30and the internal bracket20are not coincident according to operation of the control portion100as denoted as “A”, rotation speed of the first cam42with respect to rotation speed of the camshaft30is changed.

That is, since the first slider pin24is slidable along length direction thereof with respect to the camshaft30, the pin head26is rotatable within the first slot22, the second slider pin28is rotatable within the second slot23, and the wheel key45is slidable within the pin slot29, such that the rotation speed of the first cam42with respect to the rotation speed of the camshaft30is changed when the rotation centers of the camshaft30and the internal bracket20are not coincident.

When the rotation center of the internal bracket20with respect to the camshaft30moves leftward in the drawing, the rotation speed of the first cam42is relatively faster than rotation speed of the camshaft30from phase a to phase b and from phase b to phase c, then the rotation speed of the first cam42is relatively slower than rotation speed of the camshaft30from phase c to phase d and from phase d to phase a as shown inFIG. 8.

When the rotation center of the internal bracket20with respect to the camshaft30moves rightward according to the operation of the control portion100, the rotation speed of the first cam42is relatively slower than rotation speed of the camshaft30from phase a to phase b and from phase b to phase c, then the rotation speed of the first cam42is relatively faster than rotation speed of the camshaft30from phase c to phase d and from phase d to phase a as shown inFIG. 9.

According to the relative position of the internal bracket20, timing of the first cam42to push the first roller76that is the timing of the first valve72is opened or closed is changed.

FIG. 10,FIG. 11, andFIG. 12are graphs of a valve profile of a continuous variable valve duration apparatus according to an exemplary embodiment of the present invention.

The continuous variable valve duration system according to an exemplary embodiment of the present invention may perform various valve profiles according to contacting positions of the first cam42and the first roller76, mounting angle of the first cam42and the first roller76and so on.

As shown inFIG. 10, opening time of the first valve72may be fixed while closing time of the first valve72is changed. Or the opening time of the first valve72may be changed while the closing time of the first valve72is fixed as shown inFIG. 11.

As shown inFIG. 13, peak time of the first valve72may be fixed while duration of the first valve72is changed.

As described above, a continuous variable valve duration system according to an exemplary embodiment of the present invention may vary an opening duration of a valve according to operation conditions of an engine, with a simple construction.

The continuous variable valve duration system according to an exemplary embodiment of the present invention may be reduced in size and thus an entire height of a valve train may be reduced.

Since the continuous variable valve duration system may be applied to a conventional engine without excessive modification, thus productivity may be enhance and production cost may be reduced.