US20120118251A1 - Hydraulic variable valve lift apparatus - Google Patents

Abstract

A hydraulic pressure variable valve lift apparatus may include a housing that a piston chamber that one side thereof is opened is formed, a valve operating piston that is slidably disposed in the piston chamber and one end thereof is connected to a valve for opening/closing a port, and an EHV hydraulic pump that is configured to supply the piston chamber with oil, wherein a first oil passage is formed between the EHV hydraulic pump and the piston chamber on as to supply a side surface of the piston chamber with oil, and an orifice hole is formed from a piston side surface of the valve operating piston to a piston upper end surface. Accordingly, the valve lift amount can be varied according to the operating condition of the engine, a hydraulic pressure variable valve lift apparatus reduces an impact at a moment when the valve is closed by having a valve lift formed a ramp profile and does not require accurate process of multi orifice and thereby decreases a production cost.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0112299 filed Nov. 11, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.
BACKGROUND OF INVENTION
• 1. Field of Invention
• The present invention relates to a valve lift apparatus. More particularly, the present invention relates to a hydraulic pressure variable valve lift apparatus that varies lift mount of a valve for opening/closing a port of an internal combustion engine.
• 2. Description of Related Art
• An internal combustion engine takes fuel/air into a combustion chamber and combusts them to generate power. An intake valve is opened by a cam shaft to suck in the air and the air is supplied into the combustion chamber while the intake valve is opened.
• Also, an exhaust valve is lifted by a camshaft and the combustion gas is exhausted from the combustion chamber while the exhaust valve is opened.
• An optimal operation of the intake valves and the exhaust valves depends on a rotation speed of the engine. That is, an optimum lift or optimum opening/closing timing of the valves depends on the rotation speed of the engine. Researches has been undertaken on a variable valve lift (VVL) apparatus that enables different valve lifts depending on the engine speed so as to achieve such an optimal valve operation depending on the rotation speed of the engine.
• Meanwhile, since a CVVL that is broadly used includes a link, an eccentric cam, a control shaft, and so on and the number of components is large, the inertial weight and the accumulated tolerance become larger and there is a drawback in developing moving characteristics of the CVVL system.
• Also, since the valve of the cylinder is simultaneously controlled by the same camshaft, the free valve movement is restricted.
• The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
SUMMARY OF INVENTION
• Various aspects of the present invention provide for a hydraulic pressure variable valve lift apparatus having advantages of that is able to adjust a valve lift amount according to the operating condition of an engine and reducing an impact at the moment when the valve is closed such that a valve lift forms a lamp profile
• A hydraulic pressure variable valve lift apparatus, according to various aspects of the present invention may include a housing that a piston chamber that one side thereof is opened is formed, a valve operating piston that is slidably disposed in the piston chamber and one end thereof is connected to a valve for opening/closing a port, and an EHV hydraulic pump that is configured to supply the piston chamber with oil, wherein a first oil passage is formed between the EHV hydraulic pump and the piston chamber so as to supply a side surface of the piston chamber with oil, and an orifice hole is formed from a piston side surface of the valve operating piston to a piston upper end surface.
• One side of the first oil passage may be connected to a hydraulic pressure line and a first check valve is disposed at the main oil passage so as to prevent the oil from being flown backward.
• A second oil passage that is diverged from the first oil passage and may be connected to the piston chamber is formed and a second check valve is disposed at the second oil passage so as to prevent the oil from being flown backward. The second oil passage may be connected to a chamber upper end surface of the piston chamber.
• The second oil passage may be connected to the other side of the piston chamber corresponding to the first oil passage.
• The first oil passage may be connected to a side surface of the piston chamber with at least L1 from a chamber upper end surface of the piston chamber, the second oil passage is connected to a side surface of the piston chamber with at least L2 from a chamber upper end surface of the piston chamber, and the length of the L1 is longer than that of the L2.
• The second check valve may include a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that small amount of oil flows backward or forward.
• An orifice check valve may be disposed at the orifice hole such that the oil flux that is supplied to the piston chamber through the orifice hole is limited and the supplied oil is prevented from being flown backward.
• The orifice check valve may include a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that small amount of oil flows backwards or forward.
• The first oil passage may be connected to a hydraulic pressure release line, includes an oil control valve is disposed at the hydraulic pressure release line so as to open/close the hydraulic pressure release line, and an accumulator that is disposed at a downstream side of the oil control valve in the hydraulic pressure release line and temporally stores the hydraulic pressure that is released.
• The accumulator may include an accumulator piston that is slidably disposed in the accumulator chamber that is formed in one side of the hydraulic pressure release line and an accumulator spring that elastically supports the accumulator piston.
• As stated above, a hydraulic pressure variable valve lift apparatus according to various aspects of the present invention have the valve lift amount be varied according to the operating condition of the engine.
• A hydraulic pressure variable valve lift apparatus according to various aspects of the present invention reduces an impact at a moment when the valve is closed by having a valve lift formed a ramp profile.
• A hydraulic pressure variable valve lift apparatus according to various aspects of the present invention does not require accurate process of multi orifice and thereby decreases a production cost.
• The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of an exemplary hydraulic pressure variable valve lift apparatus according to the present invention.
• FIG. 2A toFIG. 2E are showing operating conditions of an exemplary hydraulic pressure variable valve lift apparatus according to the present invention.
• FIG. 3 is a partial cross-sectional view of an exemplary hydraulic pressure variable valve lift apparatus according to the present invention.
• FIG. 4 is a partial cross-sectional view of another exemplary hydraulic pressure variable valve lift apparatus according to the present invention.
• FIG. 5 is a partial cross-sectional view of another exemplary hydraulic pressure variable valve lift apparatus according to the present invention.
DETAILED DESCRIPTION
• Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.
• Referring toFIG. 1, a hydraulic pressure variable valve lift apparatus includes housing.
• Apiston chamber135, which is opened in a lower side, is formed, in thehousing120, avalve operating piston130 is disposed in thepiston chamber135, a hydraulic pressure gap adjuster110 (e.g., HLA: hydraulic lash adjuster) is disposed at a lower side of thevalve operating piston130, and the hydraulicpressure gap adjuster110 is connected to avalve100.
• Thevalve100 moves up and down together with the hydraulic pressure gap adjuster110 and thevalve operating piston130.
• An EHVhydraulic pump155 is prepared on thehousing120 and the EHVhydraulic pump155 includes an EHV piston155A and acamshaft155b.
• The EHV is an abbreviation of Electro Hydraulic Valve.
• Apump chamber158 is formed in the housing, which is spaced apart from thepiston chamber135 to be opened to a side of the housing, the EHV piston155A is inserted into thepump chamber158, and thecamshaft155bis disposed corresponding to an outside end portion of the EHV piston155A.
• Further, areturn spring157 returns the EHV piston155A that is inserted into thepump chamber158 in a central direction of thecamshaft155b.
• Accordingly, as thecamshaft155brotates, the cam have the EVH piston155A be inserted into thepump chamber158 and oil pressure of the pump chamber is increased.
• Thefirst oil passage160 connects thepump chamber158 with thepiston chamber135. Particularly, thefirst oil passage160 is connected to a side surface corresponding to apiston side surface196 of thevalve operating piston130.
• Anorifice hole125 which connects thepiston side surface196 with the pistonupper end surface194 is formed in an incline in thevalve operating piston130. In this condition, oil is charged between a pistonupper end surface194 of thevalve operating piston130 and a chamberupper end surface192 thepiston chamber135 through theorifice hole125.
• As shown in drawings, in a case that thevalve operating piston130 is positioned in an upper portion of thepiston chamber135, theorifice hole125 is connected to thefirst oil passage160.
• Amain oil passage140 is formed in thehousing120 and themain oil passage140 joins a middle portion of thefirst oil passage160.
• Afirst check valve150 is disposed in the middle of themain oil passage140 and thefirst check valve150 prevents the oil of the first oil passage from being flown backward through themain oil passage140.
• Themain oil passage140 is connected to other oil line and supplements thefirst oil passage160 with oil through thefirst check valve150.
• Further, aHLA oil passage145 is diverged from themain oil line140 downstream side of thefirst check valve150 and supplies the hydraulic pressure gap adjuster110 with oil.
• A hydraulicpressure release line199 is connected to thefirst oil passage160 and anoil control valve170 and anaccumulator180 are sequentially disposed on the hydraulicpressure release line199.
• If theoil control valve170 is opened, hydraulic pressure is released to theaccumulator180 through theoil control valve170 of the hydraulicpressure release line199.
• Theaccumulator180 includes anaccumulator piston184 that is disposed in anaccumulator chamber182 and anaccumulator spring186 that elastically supports theaccumulator piston184.
• If theoil control valve170 is opened, theaccumulator piston184 moves left side that theaccumulator chamber182 is disposed by the hydraulic pressure and theaccumulator spring186 is compressed absorbing the hydraulic pressure.
• In various embodiments, thefirst check valve150 has the oil flown in one direction and sustains the flux at less than a predetermined value.
• If thecamshaft155brotates to push the EHV piston155A, oil of thepump chamber158 is supplied to thefirst oil passage160 and oil is supplied to thepiston chamber135 through theorifice hole125.
• Accordingly, thevalve operating piston130, the hydraulicpressure gap adjuster110, and thevalve100 start to move downward. In this moment, because the oil amount that is supplied through theorifice hole125 is small, thepiston chamber135 slowly moves in the early stage of the process.
• However if thevalve operating piston130 further moves downward, thefirst oil passage160 is direct connected to thepiston chamber135 not through theorifice hole125.
• Accordingly, the oil amount that is supplied to the piston chamber is increased such that thevalve operating piston130 can quickly move.
• In other words, thevalve100 is slowly opened at an early stage of the lift period and thevalve100 is quickly opened at a middle stage of the lift.
• Further, in a closing period that theoil control valve170 is opened such that thevalve100 moves upward, thevalve100 is slowly closed to reduce noise and vibration and mechanical friction and abrasion.
• FIG. 2A shows a early stage of an opening period of thevalve100, wherein oil is supplied to thefirst oil passage160 and oil is supplied to thepiston chamber135 through theorifice hole125.
• Because a diameter of theorifice hole125 is short, the oil amount that is supplied to thepiston chamber135 is small. Accordingly, thevalve100 is slowly opened forming a ramp.
• FIG. 2B shows a middle stage of the opening period of thevalve100, wherein oil is supplied to thefirst oil passage160 and the oil of thefirst oil passage160 is direct supplied to thepiston chamber135, compared to the early stage that the oil is supplied through theorifice hole125.
• In this case, thevalve operating piston130 closes a part of thefirst oil passage160.
• Referring toFIG. 2B, the first oil passage is connected to a side surface of thepiston chamber135, wherein thefirst oil passage160 is connected to a point that has a L1 distance from the chamberupper end surface192.
• FIG. 2C shows a high lift stage of thevalve100, wherein the oil is supplied to thefirst oil passage160 and the oil of thefirst oil passage160 is direct supplied to thepiston chamber135, compared with the early stage that the oil is supplied through the second check valve185 and theorifice hole125.
• In this case, since thevalve operating piston130 does not close thefirst oil passage160, the amount that is supplied to thepiston chamber135 is increased.
• FIG. 2D shows a closing stage of thevalve100, as theoil control valve170 is being opened, hydraulic pressure is released through the hydraulicpressure release line199.
• The oil starts to be released from thepiston chamber135 to thefirst oil passage160.
• In this case, since thevalve operating piston130 does not close thefirst oil passage160, the return amount that is returned from thepiston chamber135 to thefirst oil passage160 is increased.
• FIG. 2E shows a closing lamp stage of the valve, the hydraulic pressure of the oil is released through the orifice hole.
• In this case, since thevalve operating piston130 closes thefirst oil passage160 and the oil is only returned through theorifice hole125, the amount that is returned from thepiston chamber135 through thefirst oil passage160 is decreased. Accordingly, thevalve100 forms a lamp to be slowly closed.
• Referring toFIG. 3, thefirst oil passage160 is connected to one side surface of thepiston chamber135 and thesecond oil passage300 is diverged from thefirst oil passage160 to be connected to the other side surface of thepiston chamber135.
• Thefirst oil passage160 is connected to a point that has a L1 distance from the chamberupper end surface192 in the side surface of thepiston chamber135 and thesecond oil passage300 is connected to a point that has a L2 distance from the chamberupper end surface192 in the other side surface of thepiston chamber135. As shown, the length of L1 is longer than that of L2.
• Accordingly, while thevalve operating piston130 is positioned at an upper side, small amount of oil is supplied to thepiston chamber135 through theorifice hole125, next middle amount of oil is supplied through thesecond oil passage300, and finally large amount of oil is supplied through thefirst oil passage160 and thesecond oil passage300.
• Referring now toFIG. 4, which illustrates a partial cross-section of a hydraulic pressure variable valve lift apparatus similar to that described above, the differences of the illustrated apparatus are described and the overlapping descriptions are omitted.
• As shown inFIG. 4, thevalve operating piston130 is disposed to move up and down in thepiston chamber135 and thefirst oil passage160 is connected to a side surface of thepiston chamber135.
• Anorifice hole410 is formed from a side surface of thevalve operating piston130 to the pistonupper end surface194 and anorifice check valve400 is disposed on theorifice hole420.
• Theorifice check valve400 restricts the flux of the oil that is supplied to thepiston chamber135 from the first oil passage through theorifice hole420 and prevents the oil of thepiston chamber135 from being flown backward thefirst oil passage160.
• As shown in (a) ofFIG. 4, a ball of theorifice check valve400 is opened in a forward direction and oil is supplied to thepiston chamber135 through thefirst oil passage160 and theorifice hole420 such that thevalve operating piston130 moves downward.
• As shown in (b) ofFIG. 4, a ball of theorifice check valve400 is closed in a reverse direction and oil of thepiston chamber135 is exhausted to thefirst oil passage160 through aball orifice410 that is formed in the ball of theorifice check valve400 such that thevalve operating piston130 slowly moves upward.
• Referring now toFIG. 5, which illustrates a partial cross-section of a hydraulic pressure variable valve lift apparatus similar to that described above, the differences of the illustrated apparatus are described and the overlapping descriptions are omitted.
• As shown inFIG. 5, thevalve operating piston130 is disposed in thepiston chamber135 of thehousing120 to move up and down, thefirst oil passage160 is connected to a side surface of thepiston chamber135, and thesecond oil passage500 is diverged from thefirst oil passage160 to be connected to an upper end surface of thepiston chamber135.
• Thesecond check valve510 is disposed on thesecond oil passage500 to prevent the oil of thepiston chamber135 from being flown backward thefirst oil passage160. In this case, thecheck valve510 does not completely cut off the reverse direction flow.
• As shown in detail (a) ofFIG. 5, a ball of thesecond check valve510 is opened in a forward direction and oil starts to be supplied to thepiston chamber135 through thesecond oil passage500 such that thevalve operating piston130 starts to move downward.
• As shown in detail (b) ofFIG. 5, a ball of thesecond check valve510 is closed in a reverse direction and oil of thepiston chamber135 is exhausted to thefirst oil passage160 through aball orifice520 that is formed in the ball of thesecond check valve510 such that thevalve operating piston130 slowly moves upward.
• For convenience in explanation and accurate definition in the appended claims, the terms upper or lower, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.
• The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.

Claims (11)

1. A hydraulic pressure variable valve lift apparatus comprising:

a housing including one opened side and forming a piston chamber;

a valve operating piston slidably disposed in the piston chamber and one end thereof is connected to a valve for opening/closing a port; and

an EHV hydraulic pump configured to supply the piston chamber with oil,

wherein a first oil passage is formed between the EHV hydraulic pump and the piston chamber supplies a side surface of the piston chamber with oil, and an orifice hole is formed from a piston side surface of the valve operating piston to a piston upper end surface.

2. The apparatus ofclaim 1, wherein one side of the first oil passage is connected to a hydraulic pressure line and a first check valve is disposed at the main oil passage to prevent the oil from being flown backward.

3. The apparatus ofclaim 1, wherein a second oil passage diverging from the first oil passage and is connected to the piston chamber is formed and a second check valve is disposed at the second oil passage so as to prevent the oil from flowing backward.

4. The apparatus ofclaim 3, wherein the second oil passage is connected to a chamber upper end surface of the piston chamber.

5. The apparatus ofclaim 3, wherein the second oil passage is connected to the other side of the piston chamber corresponding to the first oil passage.

6. The apparatus ofclaim 5, wherein the first oil passage is connected to a side surface of the piston chamber with at least L1 from a chamber upper end surface of the piston chamber, the second oil passage is connected to a side surface of the piston chamber with at least L2 from a chamber upper end surface of the piston chamber, and the length of the L1 is longer than that of the L2.

7. The apparatus ofclaim 3, wherein the second check valve includes a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that little oil flows backward or forward.

8. The apparatus ofclaim 1, wherein an orifice check valve is disposed at the orifice hole such that the oil flux supplied to the piston chamber through the orifice hole is limited and the supplied oil is prevented from being flowing backward.

9. The apparatus ofclaim 8, wherein the orifice check valve includes a check ball for preventing back flowing and a check valve orifice is formed in the check ball such that small amount of oil flows backwards or forward.

10. The apparatus ofclaim 1, wherein the first oil passage is connected to a hydraulic pressure release line, includes:

an oil control valve is disposed at the hydraulic pressure release line to open/close the hydraulic pressure release line; and

an accumulator disposed at a downstream side of the oil control valve in the hydraulic pressure release line and temporarily storing the hydraulic pressure that is released.

11. The apparatus ofclaim 10, wherein the accumulator includes an accumulator piston slidably disposed in the accumulator chamber formed in one side of the hydraulic pressure release line and an accumulator spring that elastically supports the accumulator piston.

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