Patent Grant
8408173
The present application claims priority to Korean Patent Application No. 10-2009-0120098 filed in the Korean Intellectual Property Office on Dec. 4, 2009, the entire contents of which is incorporated herein for all purposes by this reference.
1. Field of the Invention
The present invention relates to a variable valve lift apparatus. More particularly, the present invention relates to an electro-hydraulic variable valve lift apparatus.
2. Description of Related Art
An internal combustion engine generates power by burning fuel in a combustion chamber in 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.
An 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/closing timing of the valves depends on the rotation speed of the engine. In order to achieve such an optimal valve operation depending on the rotation speed of the engine, various researches have been undertaken. For example, research has been undertaken for a variable valve lift (VVL) apparatus that enables different lifts depending on an engine speed, and for a variable valve timing (VVT) apparatus that opens/closes the valves with different timing depending on the engine speed.
The information disclosed in this Background of the Invention 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.
An electro-hydraulic variable valve lift apparatus may include a valve unit housing of which a guide protrude portion is formed therein, a main piston which is slidably disposed in the valve unit housing and defines a valve adjusting oil chamber with the valve unit housing, a main spring which is disposed within the valve adjusting oil chamber and elastically supports the main piston on the guide protrude portion, a dependent piston which is slidably disposed within the valve unit housing, is guided along the guide protrude portion, reciprocates according to reciprocation of the main piston, and opens a valve, and a main oil supply portion which selectively supplies hydraulic pressure to the valve adjusting oil chamber.
The dependent piston may include a first dependent piston body guided along the guide protrude portion, and a second dependent piston body guided along the valve unit housing, wherein the dependent piston may further include a valve lash adjusting piston which is disposed within the second dependent piston body and defines a valve lash adjusting chamber with the second dependent piston body, a valve lash adjusting spring which is disposed within the second dependent piston body and elastically supports the valve lash adjusting piston, and a valve lash adjusting oil supply portion which supplies oil to the valve lash adjusting chamber.
The apparatus may further include a check valve which is disposed between the valve lash adjusting oil supply portion and the valve lash adjusting chamber.
A plurality of grooves may be formed to the first dependent piston body along reciprocal motion direction of the dependent piston, wherein the plurality of grooves is formed on an outer circumference of the first dependent piston body.
A plurality of grooves is formed to the first dependent piston body along reciprocal motion direction of the dependent piston and at least one groove is longer than the other grooves to be fluid-connected to the valve adjusting oil chamber, wherein the plurality of grooves are formed on an outer circumference of the first dependent piston body.
The guide protrude portion, the second dependent piston body and the valve unit housing may define an auxiliary chamber therebetween, and a first impact reducing oil passage may be formed to the dependent piston and connects the valve adjusting oil chamber and the auxiliary chamber, wherein the apparatus further includes a second impact reducing oil passage which is diverged from the first impact reducing oil passage toward the guide protrude portion such that the second impact reducing oil passage is selectively blocked by the guide protrude portion in accordance with reciprocal motion of the dependent piston.
In another aspect of the present invention, the electro-hydraulic variable valve lift apparatus may include a valve unit housing, a main piston which is slidably disposed in the valve unit housing and defines a valve adjusting oil chamber with the valve unit housing, a main spring which is disposed within the valve adjusting oil chamber and elastically supports the main piston, a dependent piston which is guided along the valve unit housing, reciprocates according to reciprocation of the main piston, and opens a valve, and a main oil supply portion which supplies hydraulic pressure to the valve adjusting oil chamber, wherein the apparatus further includes a guide protrude portion formed to the valve unit housing, and the dependent piston may include a first dependent piston body guided along the guide protrude portion, and a second dependent piston body guided along the valve unit housing, wherein a plurality of grooves are formed to the first dependent piston body along reciprocal motion direction of the dependent piston.
The plurality of grooves may be formed on an outer circumference of the first dependent piston body.
The guide protrude portion may be disposed in the valve unit housing and the main spring is positioned between the guide protrude portion and the main piston.
The apparatus may further include a guide protrude portion formed to the valve unit housing, and the dependent piston may include a first dependent piston body guided along the guide protrude portion, and a second dependent piston body guided along the valve unit housing, wherein the guide protrude portion, the second dependent piston body and the valve unit housing define an auxiliary chamber therebetween, a first impact reducing oil passage is formed to the dependent piston for connecting the valve adjusting oil chamber and the auxiliary chamber, and a second impact reducing oil passage is diverged from the first impact reducing oil passage toward the guide protrude portion such that the second impact reducing oil passage is selectively blocked by the guide protrude portion in accordance with reciprocal motion of the dependent piston, wherein the guide protrude portion is disposed in the valve unit housing and the main spring is positioned between the guide protrude portion and the main piston.
The electro-hydraulic variable valve lift apparatus according to exemplary embodiments of the present invention may be realized with simple elements and simple oil passages so that manufacturing cost can be reduce and impacts of opening and closing of a valve can be reduced.
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 of the Invention, which together serve to explain certain principles of the present invention.
It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.
In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.
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
The dependent piston 40 includes a first dependent piston body 42 guided along the guide protrude portion 15 and a second dependent piston body 44 guided along the valve unit housing 10.
The dependent piston 40, in the first exemplary embodiment of the present invention, includes a valve lash adjusting piston 60 which is disposed within the dependent piston 40 and defines a valve lash adjusting chamber 55 with the dependent piston 40, a valve lash adjusting spring 65 which is disposed within the dependent piston 40 and elastically supports the valve lash adjusting piston 60 and a valve lash adjusting oil supply portion 70 which supplies oil to the valve lash adjusting chamber 55.
In an exemplary embodiment of the present invention, the apparatus may further include a check valve 85 which is disposed between the valve lash adjusting oil supply portion 70 and the valve lash adjusting chamber 55.
A plurality of grooves 46 may be formed to the first dependent piston body 42 along reciprocal motion direction of the dependent piston 40 and at least one groove 47 may be longer than the other groove 46.
Hereinafter, operations of the electro-hydraulic variable valve apparatus according to the first exemplary embodiment of the present invention will be described. The main oil supply portion 50 supplies oil to the valve adjusting oil chamber 25, and a cam 201 (referring to
In this moment, the oil may be gradually leaked between the guide protrude portion 15 and the groove 46 and 47 formed to the first dependent piston body 42 so that impacts of opening and closing of the valve 90 can be reduced.
Supplying oil amount of the main oil supply portion 50 can be controlled by an ECU (electronic control unit), and the operations of the ECU is well known in the art so further detailed explanations will be omitted.
The valve lash adjusting oil supply portion 80 can supply oil to the valve lash adjusting chamber 55 through a valve lash adjusting oil passage 75, so that an additional HLA (hydraulic lash adjuster) does not need to be equipped.
Referring to
The dependent piston 140 includes a first dependent piston body 142 guided along the guide protrude portion 115 and a second dependent piston body 144 guided along the valve unit housing 110.
A plurality of grooves 146 may be formed to the first dependent piston body 142 along reciprocal motion direction of the dependent piston 140 and at least one groove 147 may be longer than the other groove 146.
Comparing to the first exemplary embodiment of the present invention, the electro-hydraulic variable valve apparatus according to the second exemplary embodiment of the present invention does not include the valve lash adjusting piston 60 and the valve lash adjusting oil supply portion 70 so that elements and scheme can be simplified and manufacturing cost can be reduced, too.
Except for operations of the valve lash adjusting comparing to the first exemplary embodiment of the present invention, detailed explanation of the operation of the electro-hydraulic variable valve apparatus according to the second exemplary embodiment of the present invention will be omitted.
Referring to
The dependent piston 240 includes a first dependent piston body 242 guided along the guide protrude portion 215 and a second dependent piston body 244 guided along the valve unit housing 210.
The guide protrude portion 215 and the second dependent piston body 244 defines an auxiliary chamber 270 and a first impact reducing oil passage 260 is formed to the dependent piston 240 for connecting the valve adjusting oil chamber 225 and the auxiliary chamber 270. The apparatus further include a second impact reducing oil passage 265 which is diverged from the first impact reducing oil passage 260 to the guide protrude portion 215.
The first impact reducing oil passage 260 and the second impact reducing oil passage 265 allow partial oil to be gradually leaked out to reduce impact in closing and opening of the valve 290 when a cam 201 pushes the main piston 220. Especially the second impact reducing oil passage 265 can be closed and opened by the guide protrude portion 215 so that impact and vibration induced by opening and closing of the valve 290 can be prevented.
As shown
Referring to
And thus, as shown in
As described above, the electro-hydraulic variable valve lift apparatus according to the exemplary embodiments of the present invention may simplify elements so that manufacturing cost can be reduced. And impacts of opening and closing of the valve can be reduced and early closing of the valve can be induced when it is required so that engine performance can be enhanced.
For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” 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 |
|---|---|---|---|
| 10-2009-0120098 | Dec 2009 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4287977 | Haga et al. | Sep 1981 | A |
| 4796573 | Wakeman et al. | Jan 1989 | A |
| Number | Date | Country |
|---|---|---|
| 1995-0014404 | Nov 1995 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20110132301 A1 | Jun 2011 | US |
