Patent Application
20120118251
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.
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.
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.
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 to
A piston chamber 135, which is opened in a lower side, is formed, in the housing 120, a valve operating piston 130 is disposed in the piston chamber 135, a hydraulic pressure gap adjuster 110 (e.g., HLA: hydraulic lash adjuster) is disposed at a lower side of the valve operating piston 130, and the hydraulic pressure gap adjuster 110 is connected to a valve 100.
The valve 100 moves up and down together with the hydraulic pressure gap adjuster 110 and the valve operating piston 130.
An EHV hydraulic pump 155 is prepared on the housing 120 and the EHV hydraulic pump 155 includes an EHV piston 155A and a camshaft 155b.
The EHV is an abbreviation of Electro Hydraulic Valve.
A pump chamber 158 is formed in the housing, which is spaced apart from the piston chamber 135 to be opened to a side of the housing, the EHV piston 155A is inserted into the pump chamber 158, and the camshaft 155b is disposed corresponding to an outside end portion of the EHV piston 155A.
Further, a return spring 157 returns the EHV piston 155A that is inserted into the pump chamber 158 in a central direction of the camshaft 155b.
Accordingly, as the camshaft 155b rotates, the cam have the EVH piston 155A be inserted into the pump chamber 158 and oil pressure of the pump chamber is increased.
The first oil passage 160 connects the pump chamber 158 with the piston chamber 135. Particularly, the first oil passage 160 is connected to a side surface corresponding to a piston side surface 196 of the valve operating piston 130.
An orifice hole 125 which connects the piston side surface 196 with the piston upper end surface 194 is formed in an incline in the valve operating piston 130. In this condition, oil is charged between a piston upper end surface 194 of the valve operating piston 130 and a chamber upper end surface 192 the piston chamber 135 through the orifice hole 125.
As shown in drawings, in a case that the valve operating piston 130 is positioned in an upper portion of the piston chamber 135, the orifice hole 125 is connected to the first oil passage 160.
A main oil passage 140 is formed in the housing 120 and the main oil passage 140 joins a middle portion of the first oil passage 160.
A first check valve 150 is disposed in the middle of the main oil passage 140 and the first check valve 150 prevents the oil of the first oil passage from being flown backward through the main oil passage 140.
The main oil passage 140 is connected to other oil line and supplements the first oil passage 160 with oil through the first check valve 150.
Further, a HLA oil passage 145 is diverged from the main oil line 140 downstream side of the first check valve 150 and supplies the hydraulic pressure gap adjuster 110 with oil.
A hydraulic pressure release line 199 is connected to the first oil passage 160 and an oil control valve 170 and an accumulator 180 are sequentially disposed on the hydraulic pressure release line 199.
If the oil control valve 170 is opened, hydraulic pressure is released to the accumulator 180 through the oil control valve 170 of the hydraulic pressure release line 199.
The accumulator 180 includes an accumulator piston 184 that is disposed in an accumulator chamber 182 and an accumulator spring 186 that elastically supports the accumulator piston 184.
If the oil control valve 170 is opened, the accumulator piston 184 moves left side that the accumulator chamber 182 is disposed by the hydraulic pressure and the accumulator spring 186 is compressed absorbing the hydraulic pressure.
In various embodiments, the first check valve 150 has the oil flown in one direction and sustains the flux at less than a predetermined value.
If the camshaft 155b rotates to push the EHV piston 155A, oil of the pump chamber 158 is supplied to the first oil passage 160 and oil is supplied to the piston chamber 135 through the orifice hole 125.
Accordingly, the valve operating piston 130, the hydraulic pressure gap adjuster 110, and the valve 100 start to move downward. In this moment, because the oil amount that is supplied through the orifice hole 125 is small, the piston chamber 135 slowly moves in the early stage of the process.
However if the valve operating piston 130 further moves downward, the first oil passage 160 is direct connected to the piston chamber 135 not through the orifice hole 125.
Accordingly, the oil amount that is supplied to the piston chamber is increased such that the valve operating piston 130 can quickly move.
In other words, the valve 100 is slowly opened at an early stage of the lift period and the valve 100 is quickly opened at a middle stage of the lift.
Further, in a closing period that the oil control valve 170 is opened such that the valve 100 moves upward, the valve 100 is slowly closed to reduce noise and vibration and mechanical friction and abrasion.
Because a diameter of the orifice hole 125 is short, the oil amount that is supplied to the piston chamber 135 is small. Accordingly, the valve 100 is slowly opened forming a ramp.
In this case, the valve operating piston 130 closes a part of the first oil passage 160.
Referring to
In this case, since the valve operating piston 130 does not close the first oil passage 160, the amount that is supplied to the piston chamber 135 is increased.
The oil starts to be released from the piston chamber 135 to the first oil passage 160.
In this case, since the valve operating piston 130 does not close the first oil passage 160, the return amount that is returned from the piston chamber 135 to the first oil passage 160 is increased.
In this case, since the valve operating piston 130 closes the first oil passage 160 and the oil is only returned through the orifice hole 125, the amount that is returned from the piston chamber 135 through the first oil passage 160 is decreased. Accordingly, the valve 100 forms a lamp to be slowly closed.
Referring to
The first oil passage 160 is connected to a point that has a L1 distance from the chamber upper end surface 192 in the side surface of the piston chamber 135 and the second oil passage 300 is connected to a point that has a L2 distance from the chamber upper end surface 192 in the other side surface of the piston chamber 135. As shown, the length of L1 is longer than that of L2.
Accordingly, while the valve operating piston 130 is positioned at an upper side, small amount of oil is supplied to the piston chamber 135 through the orifice hole 125, next middle amount of oil is supplied through the second oil passage 300, and finally large amount of oil is supplied through the first oil passage 160 and the second oil passage 300.
Referring now to
As shown in
An orifice hole 410 is formed from a side surface of the valve operating piston 130 to the piston upper end surface 194 and an orifice check valve 400 is disposed on the orifice hole 420.
The orifice check valve 400 restricts the flux of the oil that is supplied to the piston chamber 135 from the first oil passage through the orifice hole 420 and prevents the oil of the piston chamber 135 from being flown backward the first oil passage 160.
As shown in (a) of
As shown in (b) of
Referring now to
As shown in
The second check valve 510 is disposed on the second oil passage 500 to prevent the oil of the piston chamber 135 from being flown backward the first oil passage 160. In this case, the check valve 510 does not completely cut off the reverse direction flow.
As shown in detail (a) of
As shown in detail (b) of
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-0112299 | Nov 2010 | KR | national |
