Patent Application
20140041605
The present application claims priority to Korean Patent Application No. 10-2012-0086706 filed on Aug. 8, 2012, the entire contents of which is incorporated herein for all purposes by this reference.
1. Field of the Invention
The present invention relates to an electro-hydraulic variable valve lift apparatus and, more particularly, to an electro-hydraulic variable valve lift apparatus adaptive to have a simplified oil circuit to reduce oil flow path resistance.
2. Description of Related Art
An internal combustion engine takes in fuel and air to a combustion chamber and burns the same to generate power. In case of sucking air, an intake valve is operated by driving a cam shaft, and while the intake valve is open, air is sucked into the combustion chamber. Also, an exhaust valve is operated by driving the cam shaft, and while the exhaust valve is open, air is expelled from the combustion chamber.
However, an optimal operation of the intake valve and the exhaust valve varies according to a rotation speed of an engine. Namely, an appropriate lift or valve opening/closing time varies according to a rotation speed of an engine. Thus, in order to implement an appropriate valve operation according to a rotation speed of an engine, a plurality of cams for driving valves are designed, or a variable valve lift (VVL) apparatus in which a valve is operated at a different lift according to an engine RPM, a variable valve timing (VVT), an electro-hydro valve lift (EHV), and the like, have been searched.
In case of a generally used EHV apparatus, an oil circuit for an operation thereof is complicated and resistance of oil that passes through the complicated oil circuit is problematic.
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.
Various aspects of the present invention are directed to providing an electro-hydraulic variable valve lift apparatus adaptive to have a simplified oil circuit to reduce oil flow path resistance.
In an aspect of the present invention, an electro-hydraulic variable valve lift apparatus may include a hydraulic pump body installed in an engine, a piston slidably provided in the hydraulic pump body to reciprocate therein and forming an hydraulic pump chamber together with the hydraulic pump body, an hydraulic pump cam disposed to be in contact with the piston and enabling the piston to reciprocate according to a rotation of the hydraulic pump cam, a retainer provided in the engine to be slidable along a longitudinal direction of the piston between the piston and the engine and forming a retainer chamber with the engine, a retainer spring elastically supporting the retainer, an oil control valve selectively allowing the hydraulic pump chamber and the retainer chamber to fluid-communicate with each other, and a valve opening and closing unit fluid-communicating with the hydraulic pump chamber and opened or closed according to oil pressure supplied from the hydraulic pump chamber thereto.
The retainer spring is brought into contact with the retainer and the piston to provide elastic force to the piston.
The hydraulic pump body may include a retainer hole fluid-communicating the hydraulic pump chamber with the retainer chamber, wherein the oil control valve may include an operational rod slidably mounted in the retainer chamber and selectively opens or closes the retainer hole through operation of the operational rod.
The electro-hydraulic variable valve lift apparatus may further may include an oil supply line connected to the hydraulic pump chamber and supplying oil thereto, and a check valve provided in the oil supply line.
The electro-hydraulic variable valve lift apparatus may further may include an operation line fluid-connecting the hydraulic pump chamber to the valve opening and closing unit.
The oil supply line is fluid-connected to the operation line.
The electro-hydraulic variable valve lift apparatus may further may include a piston spring provided between the piston and the hydraulic pump body in the hydraulic pump chamber to elastically support the piston.
The oil control valve implements a high lift mode by preventing the oil pressure from being released from the hydraulic pump chamber to the retainer chamber during a cycle in which the valve opening and closing unit is opened or closed.
The oil control valve implements a low lift mode by allowing the hydraulic pump chamber and the retainer chamber to be fluid-connected while the piston is lowered.
The oil control valve implements a cylinder deactivation mode by allowing the hydraulic pump chamber and the retainer chamber to be constantly fluid-connected.
In the case of the electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention, oil flow path resistance can be reduced by simplifying an oil circuit.
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.
a), 2(b) and 2(c) are views illustrating an operation of the electro-hydraulic variable valve lift apparatus in a high lift mode according to an exemplary embodiment of the present invention.
a), 3(b) and 3(c) are views illustrating an operation of the electro-hydraulic variable valve lift apparatus in a low lift mode according to an exemplary embodiment 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 the 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.
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown
As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention
Throughout the specification, unless explicitly described to the contrary, the word “include” and variations such as “includes” or “including”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
Throughout the specification, components denoted by the same reference numerals are the same components.
In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity.
An electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention includes, an hydraulic pump body 20 installed in an engine 10, a piston 30 provided to reciprocate within the hydraulic pump body 20 and forming an hydraulic pump chamber 22 together with the hydraulic pump body 20, an hydraulic pump cam 40 disposed to be in contact with the piston 30 and enabling the piston 30 to reciprocate according to a rotation thereof, a retainer 50 provided to be slidable along the piston 30 between the piston 30 and the engine 10 and forming a retainer chamber 54 with the engine 10, a retainer spring 52 elastically supporting the retainer 50, an oil control valve 60 allowing the hydraulic pump chamber 22 and the retainer chamber 54 to selectively communicate with each other, a valve opening and closing unit 70 communicating with the hydraulic pump chamber 22 and opened or closed according to oil pressure supplied from the hydraulic pump chamber 22.
Here, the engine 10 may have a concept of including a cylinder head, a valve train, and the like.
The retainer spring 52 may be brought into contact with the piston 30 and the retainer 50 to provide elastic force.
Namely, the retainer spring 52 may be interposed between the piston 30 and the retainer 50 and provide elastic force to the piston 30 and the retainer 50.
Also, the electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention may further include a piston spring 32 provided between the piston 30 and the hydraulic pump body 20 to elastically support the piston 30.
Namely, the retainer spring 52 may be interposed between the piston 30 and the retainer 50 to provide elastic force to the piston 30 and the retainer 50, or another piston spring 32 may be provided to elastically support the piston 30.
The hydraulic pump body 20 includes a retainer hole 24 communicating with the retainer chamber 54, and the oil control valve 60 may include an operation rod 62 and selectively open and close the retainer hole 24 through the operation rod 62.
The electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention may further include an oil supply line 14 supplying oil to the hydraulic pump chamber 22 and a check valve 16 provided in the oil supply line 14.
In the electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention, oil may be leaked during an operation process of the electro-hydraulic variable valve lift apparatus, and oil supplied from an oil supply unit may be supplied to the hydraulic pump chamber 22 through the oil supply line 14, whereby oil within the electro-hydraulic variable valve lift apparatus can be maintained at a predetermined level. Here, the check valve 16 prevents oil from flowing backward from the hydraulic pump chamber 22.
The valve opening and closing unit 70 may include a brake unit 72 implementing smooth opening and closing of a valve profile in a start position and an end position of the valve profile, a valve 74 opened or closed according to oil pressure supplied from the hydraulic pump chamber 22, and a valve spring 76 elastically supporting the valve 74.
When high pressure is formed within the hydraulic pump chamber 22 according to an operation of the hydraulic pump cam 40, the high pressure oil operates the valve 74 through an operation hole 26 formed in the hydraulic pump body 20 and an operation line 12 to open the valve 74.
Here, the operation and configuration of the brake unit 72, the valve 74, and the valve spring 76 are obvious to a person skilled in the art, so a detailed description thereof will be omitted.
a), 2(b) and 2(c) are views illustrating an operation of the electro-hydraulic variable valve lift apparatus in a high lift mode according to an exemplary embodiment of the present invention, and
Hereinafter, an operation of the electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention will be described with reference to the figures.
Referring to
Namely, as illustrated in
Referring to
Namely, as illustrated in
Thus, as illustrated in
Thereafter, as illustrated in
Then, the oil within the retainer chamber 54 is introduced again into the hydraulic pump chamber 22 and the operation rod 62 closes the retainer hole 24, entering a preparation stage for implementing a next cycle.
Here, the operation of the oil control valve 60 in the rotation position of the hydraulic pump cam 40 as illustrated in
The oil control valve 60 may allow the oil pump chamber 22 and the retainer chamber 54 to constantly communicate with each other, regardless of a rotational position of the hydraulic pump cam 40, to implement a cylinder deactivation (CDA) mode.
Namely, when the operation rod 62 maintains an open state, the retainer 60 reciprocate vertically according to a rotation of the hydraulic pump cam 40. However, since oil is not supplied to the valve opening and closing unit 70, the valve 74 is not opened or closed.
As described above, in the case of the electro-hydraulic variable valve lift apparatus according to an exemplary embodiment of the present invention, the oil circuit can be simplified, thus reducing oil flow path resistance. Also, the simple structure improves hydraulic efficiency and reduces driving friction.
Also, referring to
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 |
|---|---|---|---|
| 10-2012-0086706 | Aug 2012 | KR | national |
